SlideShare a Scribd company logo
1 of 18
Download to read offline
Sample size, importance of sample size, factors influencing sample size and
dropouts
Naveen K L
2nd Year M Pharmacy (3rd Sem)
Dept. of Pharmacology
Srinivas College Of Pharmacy
Valachil, Mangaluru.
Contents:
• Introduction
• Sample size
• Importance of sample size
• Selection of sample size
• Factors influencing sample size
• Dropouts
Introduction
• Statistics is the science of collection, presentation, analysis and
interpretation of numerical data from logical analysis.
• Biostatistics is a tool of statistics applied to the numerical data that is
derived from biological sciences.
• Everything in medical field, biostatistics explains research, diagnosis
or treatment which depends on measurement .
Sample Size
• Number of individuals or the number of observations (a sample) included
in the study is referred as sample size.
• Main goal of the selection of sample size is to make an inference about
population.
• The determination of sample size is the act of choosing the number of
observation or replicates to include in a statistical sample.
• The sample size used in the study is usually determined on the basis of
costs, time or convenience of collecting data.
(Power, Inverse function of Significance level)
Sample Size =
(absolute difference)2
Sample
Population
IMPORTANCE OF SAMPLE SIZE CALCULATION
• If the study which is too small is more likely to generate inconclusive,
incorrect or spurious results. This is because a smaller sample size will
generate or estimates higher variation and these estimates having less
useful in modelling and understanding real underlying question of interest
in a study.
• If the studies are more likely to fail due to inadequate sample size are
considered as unethical. This is because exposing human subjects or lab
animal to the possible risks associated with research. Additionally, a study
having too large faces the ethical problems and will also waste scarce
resources such as money, subjects and time.
Selection of sample size
Study
Plan
Specify
Parameter
Choose
Effect
Size
Compute
Sample
Size
Study plan
Planning the study involves
establishing the purpose of the
study
What is going to measured to
fulfil those purposes
What statistical methods and
assumption that go into
extracting those from your
study
Cont..
1)What question/s do you want to answer ?
2)What is the primary outcome of the study ?
3)What kind of the grouping structure will the study have ?
4)What type of hypothesis test will be used ?
Specify Parameters
• The analysis parameters are assumptions that need to be made about the
statistical method to make a sample size justification for the study.
• Each study design has different analysis parameters that must be estimated
in the design stage of the study.
• 2 primary types of parameters used in sample size determination
 Prespecified parameters
Unknown parameters
Eg for parameters are needed for statistical method like Significance level,
Standard deviation, intracluster correlation.
Choose effect size
• Once the analysis parameters are specified then effect of size is important for
sample size calculations.
• This is the difference in the primary outcome value used in the sample size
calculation that the clinical trail or study is designed to reliably detect.
• A common parameterisation for the effect of size is the ‘’Standardised effect
size’’
• Standardised effect size measures magnitude of treatment effect without
units allows more direct and comparable measure of the expected degree of
the effect across different studies.
• A very common standardised effect size metric is Cohen's effect size.
μ1−μ2 / σ
• Why is the effect size important in a clinical trail or study ?
• 2 main approaches for specifying the effect size
 Selection of clinically relevant difference i.e. a difference that would be
important from a clinician’s or patient’s
Select a realistic difference based on prior evidence and information.
Compute SAMPLE SIZE
• After successful specifying effect size then compute the sample size or
power for the study is done.
• Increasing sample size is associated with an increasing in power.
(Zα/2+ Zβ)2 × 2σ2
n=
(μ1-μ2)2
Where
n= required sample size
μ1= mean change from baseline in one sample
μ2 = mean change from baseline in another sample
Z α/2 = standard normal z value for significance level α
Zβ = standard normal z value for the power
Factors influencing sample size
These are the main factors which influences sample size listed as below
 Effect of size
 The homogeneity
 The risk of error
 Difference expected
 Positive character
 Degree of variation among subjects
 Level of significance desired- p value
 Power of the study desired
Dropout
• Individual from sample size or from the group of sample which may be rejected
from the study because of lack of efficacy.
• General formula for calculation of number of dropouts (N)
N= cumulative total for 1st dose in series – cumulative total for last dose in series
% Dropout rate = (N/Cumulative total for 1st dose in series)×100
 Lets consider an Example....
• Vaccination of a population of 120 people
• Cumulative total on first dose = 120
• Cumulative total last dose in series = 103
• N = 17
• % Dropout= 14.16
References
1. Habib A, Johargy A, Mahmood K, Humma, Design and determination of
the sample size in medical research. IOSR-JDMS.2014;13(5):21-31
2. https://www.statsols.com/how-to-use-a-sample-size-calculator retrieved
on 21/07/2020 at 03.00 p.m.
3. https://www.scribd.com/doc/98854480/factors-Affecting-Sample-Size
retrieved on 22/07/2020 at 10.30 a.m.
4. https://blog.statsols.com/why-is-sample-size-important/?hs_amp=true
retrieved on 22/07/2020 at 11.30 a.m.
5. https://youtu.be/Lq5TBf30uFM retrieved on 22/07/2020 at 12.30 a.m.
6. https://www.slideshare.net/mobile/indiandentalacademy/bio-statistics-
61741733 retrieved on 22/07/2020 at 12.14 a.m.
Thank You

More Related Content

What's hot

Cross over design, Placebo and blinding techniques
Cross over design, Placebo and blinding techniques Cross over design, Placebo and blinding techniques
Cross over design, Placebo and blinding techniques Dinesh Gangoda
 
Sample size
Sample sizeSample size
Sample sizezubis
 
non parametric statistics
non parametric statisticsnon parametric statistics
non parametric statisticsAnchal Garg
 
Research methodology unit-1
Research methodology unit-1Research methodology unit-1
Research methodology unit-1Gnanaprakasam
 
General research methodology mpharm
General research methodology  mpharmGeneral research methodology  mpharm
General research methodology mpharmAlkaDiwakar
 
NON-PARAMETRIC TESTS by Prajakta Sawant
NON-PARAMETRIC TESTS by Prajakta SawantNON-PARAMETRIC TESTS by Prajakta Sawant
NON-PARAMETRIC TESTS by Prajakta SawantPRAJAKTASAWANT33
 
Medical research methodology
Medical research methodologyMedical research methodology
Medical research methodologyWalid Ahmed
 
Wilcoxon signed rank test
Wilcoxon signed rank testWilcoxon signed rank test
Wilcoxon signed rank testBiswash Sapkota
 
Crossover design ppt
Crossover design pptCrossover design ppt
Crossover design pptHARISH J
 
M. Pharm: Research Methodology and biostatics
M. Pharm: Research Methodology and biostatics M. Pharm: Research Methodology and biostatics
M. Pharm: Research Methodology and biostatics SONALI PAWAR
 
Medical Research Pharmacy
Medical Research PharmacyMedical Research Pharmacy
Medical Research PharmacyAparna Yadav
 
P value, Power, Type 1 and 2 errors
P value, Power, Type 1 and 2 errorsP value, Power, Type 1 and 2 errors
P value, Power, Type 1 and 2 errorsRizwan S A
 
Blinding in clinical trilas
Blinding in clinical trilas Blinding in clinical trilas
Blinding in clinical trilas Tarek Tawfik Amin
 

What's hot (20)

Cross over design, Placebo and blinding techniques
Cross over design, Placebo and blinding techniques Cross over design, Placebo and blinding techniques
Cross over design, Placebo and blinding techniques
 
Student t test
Student t testStudent t test
Student t test
 
Sample size
Sample sizeSample size
Sample size
 
non parametric statistics
non parametric statisticsnon parametric statistics
non parametric statistics
 
Non parametric tests
Non parametric testsNon parametric tests
Non parametric tests
 
Research methodology unit-1
Research methodology unit-1Research methodology unit-1
Research methodology unit-1
 
Study designs
Study designsStudy designs
Study designs
 
Medical research
Medical researchMedical research
Medical research
 
General research methodology mpharm
General research methodology  mpharmGeneral research methodology  mpharm
General research methodology mpharm
 
Bias and errors
Bias and errorsBias and errors
Bias and errors
 
NON-PARAMETRIC TESTS by Prajakta Sawant
NON-PARAMETRIC TESTS by Prajakta SawantNON-PARAMETRIC TESTS by Prajakta Sawant
NON-PARAMETRIC TESTS by Prajakta Sawant
 
Medical research methodology
Medical research methodologyMedical research methodology
Medical research methodology
 
Wilcoxon signed rank test
Wilcoxon signed rank testWilcoxon signed rank test
Wilcoxon signed rank test
 
Crossover design ppt
Crossover design pptCrossover design ppt
Crossover design ppt
 
M. Pharm: Research Methodology and biostatics
M. Pharm: Research Methodology and biostatics M. Pharm: Research Methodology and biostatics
M. Pharm: Research Methodology and biostatics
 
Medical Research Pharmacy
Medical Research PharmacyMedical Research Pharmacy
Medical Research Pharmacy
 
P value, Power, Type 1 and 2 errors
P value, Power, Type 1 and 2 errorsP value, Power, Type 1 and 2 errors
P value, Power, Type 1 and 2 errors
 
Declaration of helsinki (Pharmacology SEM-III)
Declaration of helsinki (Pharmacology SEM-III)Declaration of helsinki (Pharmacology SEM-III)
Declaration of helsinki (Pharmacology SEM-III)
 
Blinding in clinical trilas
Blinding in clinical trilas Blinding in clinical trilas
Blinding in clinical trilas
 
factorial design
factorial designfactorial design
factorial design
 

Similar to PPT on Sample Size, Importance of Sample Size,

Biostatistics_Unit_II_ResearchMethodologyBiostatistics.pptx
Biostatistics_Unit_II_ResearchMethodologyBiostatistics.pptxBiostatistics_Unit_II_ResearchMethodologyBiostatistics.pptx
Biostatistics_Unit_II_ResearchMethodologyBiostatistics.pptxPrachi Pandey
 
Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...
Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...
Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...RAHUL PAL
 
SAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptx
SAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptxSAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptx
SAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptxssuserd509321
 
Sample determinants and size
Sample determinants and sizeSample determinants and size
Sample determinants and sizeTarek Tawfik Amin
 
Sample-size-comprehensive.pptx
Sample-size-comprehensive.pptxSample-size-comprehensive.pptx
Sample-size-comprehensive.pptxssuser4eb7dd
 
Bio-Statistics in Bio-Medical research
Bio-Statistics in Bio-Medical researchBio-Statistics in Bio-Medical research
Bio-Statistics in Bio-Medical researchShinjan Patra
 
Cochrane Collaboration
Cochrane CollaborationCochrane Collaboration
Cochrane CollaborationNinian Peckitt
 
Research and Scientific Journal Publication support services | Research pape...
 Research and Scientific Journal Publication support services | Research pape... Research and Scientific Journal Publication support services | Research pape...
Research and Scientific Journal Publication support services | Research pape...Pubrica
 
Sample size & meta analysis
Sample size & meta analysisSample size & meta analysis
Sample size & meta analysisdrsrb
 
Meta analysis
Meta analysisMeta analysis
Meta analysisJunaidAKG
 
TREATMENT OF DATA_Scrd.pptx
TREATMENT OF DATA_Scrd.pptxTREATMENT OF DATA_Scrd.pptx
TREATMENT OF DATA_Scrd.pptxCarmela857185
 
Sample size calculation
Sample  size calculationSample  size calculation
Sample size calculationSwati Singh
 
Sample Size Estimation and Statistical Test Selection
Sample Size Estimation  and Statistical Test SelectionSample Size Estimation  and Statistical Test Selection
Sample Size Estimation and Statistical Test SelectionVaggelis Vergoulas
 
presentation on calculation of sample size
presentation on calculation of sample sizepresentation on calculation of sample size
presentation on calculation of sample sizeRichaMishra186341
 
2_Lecture 2_Confidence_Interval_3.pdf
2_Lecture 2_Confidence_Interval_3.pdf2_Lecture 2_Confidence_Interval_3.pdf
2_Lecture 2_Confidence_Interval_3.pdfCHANSreyya1
 
Advanced Biostatistics and Data Analysis abdul ghafoor sajjad
Advanced Biostatistics and Data Analysis abdul ghafoor sajjadAdvanced Biostatistics and Data Analysis abdul ghafoor sajjad
Advanced Biostatistics and Data Analysis abdul ghafoor sajjadHeadDPT
 
Sample size estimation
Sample size estimationSample size estimation
Sample size estimationHanaaBayomy
 
Clinical Research Statistics for Non-Statisticians
Clinical Research Statistics for Non-StatisticiansClinical Research Statistics for Non-Statisticians
Clinical Research Statistics for Non-StatisticiansBrook White, PMP
 

Similar to PPT on Sample Size, Importance of Sample Size, (20)

Biostatistics_Unit_II_ResearchMethodologyBiostatistics.pptx
Biostatistics_Unit_II_ResearchMethodologyBiostatistics.pptxBiostatistics_Unit_II_ResearchMethodologyBiostatistics.pptx
Biostatistics_Unit_II_ResearchMethodologyBiostatistics.pptx
 
Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...
Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...
Biostatistics_Unit_II_Research Methodology & Biostatistics_M. Pharm (Pharmace...
 
SAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptx
SAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptxSAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptx
SAMPLE SIZE CALCULATION IN DIFFERENT STUDY DESIGNS AT.pptx
 
Sample determinants and size
Sample determinants and sizeSample determinants and size
Sample determinants and size
 
Sample size determination
Sample size determinationSample size determination
Sample size determination
 
Sample-size-comprehensive.pptx
Sample-size-comprehensive.pptxSample-size-comprehensive.pptx
Sample-size-comprehensive.pptx
 
Bio-Statistics in Bio-Medical research
Bio-Statistics in Bio-Medical researchBio-Statistics in Bio-Medical research
Bio-Statistics in Bio-Medical research
 
Cochrane Collaboration
Cochrane CollaborationCochrane Collaboration
Cochrane Collaboration
 
Research and Scientific Journal Publication support services | Research pape...
 Research and Scientific Journal Publication support services | Research pape... Research and Scientific Journal Publication support services | Research pape...
Research and Scientific Journal Publication support services | Research pape...
 
Sample size & meta analysis
Sample size & meta analysisSample size & meta analysis
Sample size & meta analysis
 
Meta analysis
Meta analysisMeta analysis
Meta analysis
 
TREATMENT OF DATA_Scrd.pptx
TREATMENT OF DATA_Scrd.pptxTREATMENT OF DATA_Scrd.pptx
TREATMENT OF DATA_Scrd.pptx
 
Sample size calculation
Sample  size calculationSample  size calculation
Sample size calculation
 
2RM2 PPT.pptx
2RM2 PPT.pptx2RM2 PPT.pptx
2RM2 PPT.pptx
 
Sample Size Estimation and Statistical Test Selection
Sample Size Estimation  and Statistical Test SelectionSample Size Estimation  and Statistical Test Selection
Sample Size Estimation and Statistical Test Selection
 
presentation on calculation of sample size
presentation on calculation of sample sizepresentation on calculation of sample size
presentation on calculation of sample size
 
2_Lecture 2_Confidence_Interval_3.pdf
2_Lecture 2_Confidence_Interval_3.pdf2_Lecture 2_Confidence_Interval_3.pdf
2_Lecture 2_Confidence_Interval_3.pdf
 
Advanced Biostatistics and Data Analysis abdul ghafoor sajjad
Advanced Biostatistics and Data Analysis abdul ghafoor sajjadAdvanced Biostatistics and Data Analysis abdul ghafoor sajjad
Advanced Biostatistics and Data Analysis abdul ghafoor sajjad
 
Sample size estimation
Sample size estimationSample size estimation
Sample size estimation
 
Clinical Research Statistics for Non-Statisticians
Clinical Research Statistics for Non-StatisticiansClinical Research Statistics for Non-Statisticians
Clinical Research Statistics for Non-Statisticians
 

More from Naveen K L

PPT on Protective Activity Of Certain Important Antioxidant
PPT on Protective Activity Of Certain Important Antioxidant PPT on Protective Activity Of Certain Important Antioxidant
PPT on Protective Activity Of Certain Important Antioxidant Naveen K L
 
OECD Guideline For Acute oral toxicity (TG 423)
OECD Guideline For Acute oral toxicity (TG 423)OECD Guideline For Acute oral toxicity (TG 423)
OECD Guideline For Acute oral toxicity (TG 423)Naveen K L
 
PPT on Vigiflow, Argus-G and Aris For ADR Reporting
PPT on Vigiflow, Argus-G and Aris For ADR ReportingPPT on Vigiflow, Argus-G and Aris For ADR Reporting
PPT on Vigiflow, Argus-G and Aris For ADR ReportingNaveen K L
 
PPT on Cellular and molecular mechanism of sex hormones
PPT on Cellular and molecular mechanism of sex hormonesPPT on Cellular and molecular mechanism of sex hormones
PPT on Cellular and molecular mechanism of sex hormonesNaveen K L
 
Animals used in Laboratory (Pharmacology) and their specific criteria
Animals used in Laboratory (Pharmacology) and their specific criteria Animals used in Laboratory (Pharmacology) and their specific criteria
Animals used in Laboratory (Pharmacology) and their specific criteria Naveen K L
 
SlideShare Presentation on Mass spectrophotometer
SlideShare Presentation on Mass spectrophotometerSlideShare Presentation on Mass spectrophotometer
SlideShare Presentation on Mass spectrophotometerNaveen K L
 
SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)
SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)
SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)Naveen K L
 
Ppt On National Programmes Related to Pharmacovigilance
Ppt On National Programmes  Related to PharmacovigilancePpt On National Programmes  Related to Pharmacovigilance
Ppt On National Programmes Related to PharmacovigilanceNaveen K L
 
SlideShare on Traditional drug design methods
 SlideShare on Traditional drug design methods  SlideShare on Traditional drug design methods
SlideShare on Traditional drug design methods Naveen K L
 
PPT On Female Reproductive Toxicology
PPT On Female Reproductive Toxicology PPT On Female Reproductive Toxicology
PPT On Female Reproductive Toxicology Naveen K L
 
Preclinical screening of anti fertility agents
Preclinical screening of anti fertility agentsPreclinical screening of anti fertility agents
Preclinical screening of anti fertility agentsNaveen K L
 
Sympathomimetics advance
Sympathomimetics advanceSympathomimetics advance
Sympathomimetics advanceNaveen K L
 
Cryopreservation
Cryopreservation Cryopreservation
Cryopreservation Naveen K L
 

More from Naveen K L (13)

PPT on Protective Activity Of Certain Important Antioxidant
PPT on Protective Activity Of Certain Important Antioxidant PPT on Protective Activity Of Certain Important Antioxidant
PPT on Protective Activity Of Certain Important Antioxidant
 
OECD Guideline For Acute oral toxicity (TG 423)
OECD Guideline For Acute oral toxicity (TG 423)OECD Guideline For Acute oral toxicity (TG 423)
OECD Guideline For Acute oral toxicity (TG 423)
 
PPT on Vigiflow, Argus-G and Aris For ADR Reporting
PPT on Vigiflow, Argus-G and Aris For ADR ReportingPPT on Vigiflow, Argus-G and Aris For ADR Reporting
PPT on Vigiflow, Argus-G and Aris For ADR Reporting
 
PPT on Cellular and molecular mechanism of sex hormones
PPT on Cellular and molecular mechanism of sex hormonesPPT on Cellular and molecular mechanism of sex hormones
PPT on Cellular and molecular mechanism of sex hormones
 
Animals used in Laboratory (Pharmacology) and their specific criteria
Animals used in Laboratory (Pharmacology) and their specific criteria Animals used in Laboratory (Pharmacology) and their specific criteria
Animals used in Laboratory (Pharmacology) and their specific criteria
 
SlideShare Presentation on Mass spectrophotometer
SlideShare Presentation on Mass spectrophotometerSlideShare Presentation on Mass spectrophotometer
SlideShare Presentation on Mass spectrophotometer
 
SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)
SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)
SlideShare On Chemotherapy of Antiviral Drugs (Pharmacology)
 
Ppt On National Programmes Related to Pharmacovigilance
Ppt On National Programmes  Related to PharmacovigilancePpt On National Programmes  Related to Pharmacovigilance
Ppt On National Programmes Related to Pharmacovigilance
 
SlideShare on Traditional drug design methods
 SlideShare on Traditional drug design methods  SlideShare on Traditional drug design methods
SlideShare on Traditional drug design methods
 
PPT On Female Reproductive Toxicology
PPT On Female Reproductive Toxicology PPT On Female Reproductive Toxicology
PPT On Female Reproductive Toxicology
 
Preclinical screening of anti fertility agents
Preclinical screening of anti fertility agentsPreclinical screening of anti fertility agents
Preclinical screening of anti fertility agents
 
Sympathomimetics advance
Sympathomimetics advanceSympathomimetics advance
Sympathomimetics advance
 
Cryopreservation
Cryopreservation Cryopreservation
Cryopreservation
 

Recently uploaded

Screening for colorectal cancer AAU.pptx
Screening for colorectal cancer AAU.pptxScreening for colorectal cancer AAU.pptx
Screening for colorectal cancer AAU.pptxtadehabte
 
Role of medicinal and aromatic plants in national economy PDF.pdf
Role of medicinal and aromatic plants in national economy PDF.pdfRole of medicinal and aromatic plants in national economy PDF.pdf
Role of medicinal and aromatic plants in national economy PDF.pdfDivya Kanojiya
 
Apiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.pptApiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.pptkedirjemalharun
 
Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...
Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...
Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...MehranMouzam
 
Plant Fibres used as Surgical Dressings PDF.pdf
Plant Fibres used as Surgical Dressings PDF.pdfPlant Fibres used as Surgical Dressings PDF.pdf
Plant Fibres used as Surgical Dressings PDF.pdfDivya Kanojiya
 
SYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptx
SYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptxSYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptx
SYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptxdrashraf369
 
SCHOOL HEALTH SERVICES.pptx made by Sapna Thakur
SCHOOL HEALTH SERVICES.pptx made by Sapna ThakurSCHOOL HEALTH SERVICES.pptx made by Sapna Thakur
SCHOOL HEALTH SERVICES.pptx made by Sapna ThakurSapna Thakur
 
Nutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience ClassNutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience Classmanuelazg2001
 
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara RajendranMusic Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara RajendranTara Rajendran
 
epilepsy and status epilepticus for undergraduate.pptx
epilepsy and status epilepticus  for undergraduate.pptxepilepsy and status epilepticus  for undergraduate.pptx
epilepsy and status epilepticus for undergraduate.pptxMohamed Rizk Khodair
 
World-Health-Day-2024-My-Health-My-Right.pptx
World-Health-Day-2024-My-Health-My-Right.pptxWorld-Health-Day-2024-My-Health-My-Right.pptx
World-Health-Day-2024-My-Health-My-Right.pptxEx WHO/USAID
 
Presentation on General Anesthetics pdf.
Presentation on General Anesthetics pdf.Presentation on General Anesthetics pdf.
Presentation on General Anesthetics pdf.Prerana Jadhav
 
Big Data Analysis Suggests COVID Vaccination Increases Excess Mortality Of ...
Big Data Analysis Suggests COVID  Vaccination Increases Excess Mortality Of  ...Big Data Analysis Suggests COVID  Vaccination Increases Excess Mortality Of  ...
Big Data Analysis Suggests COVID Vaccination Increases Excess Mortality Of ...sdateam0
 
METHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaur
METHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaurMETHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaur
METHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaurNavdeep Kaur
 
ANEMIA IN PREGNANCY by Dr. Akebom Kidanemariam
ANEMIA IN PREGNANCY by Dr. Akebom KidanemariamANEMIA IN PREGNANCY by Dr. Akebom Kidanemariam
ANEMIA IN PREGNANCY by Dr. Akebom KidanemariamAkebom Gebremichael
 
History and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdfHistory and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdfSasikiranMarri
 
The next social challenge to public health: the information environment.pptx
The next social challenge to public health:  the information environment.pptxThe next social challenge to public health:  the information environment.pptx
The next social challenge to public health: the information environment.pptxTina Purnat
 
Phytochemical Investigation of Drugs PDF.pdf
Phytochemical Investigation of Drugs PDF.pdfPhytochemical Investigation of Drugs PDF.pdf
Phytochemical Investigation of Drugs PDF.pdfDivya Kanojiya
 
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdfMedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdfSasikiranMarri
 
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand UniversityCEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand UniversityHarshChauhan475104
 

Recently uploaded (20)

Screening for colorectal cancer AAU.pptx
Screening for colorectal cancer AAU.pptxScreening for colorectal cancer AAU.pptx
Screening for colorectal cancer AAU.pptx
 
Role of medicinal and aromatic plants in national economy PDF.pdf
Role of medicinal and aromatic plants in national economy PDF.pdfRole of medicinal and aromatic plants in national economy PDF.pdf
Role of medicinal and aromatic plants in national economy PDF.pdf
 
Apiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.pptApiculture Chapter 1. Introduction 2.ppt
Apiculture Chapter 1. Introduction 2.ppt
 
Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...
Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...
Study on the Impact of FOCUS-PDCA Management Model on the Disinfection Qualit...
 
Plant Fibres used as Surgical Dressings PDF.pdf
Plant Fibres used as Surgical Dressings PDF.pdfPlant Fibres used as Surgical Dressings PDF.pdf
Plant Fibres used as Surgical Dressings PDF.pdf
 
SYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptx
SYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptxSYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptx
SYNDESMOTIC INJURY- ANATOMICAL REPAIR.pptx
 
SCHOOL HEALTH SERVICES.pptx made by Sapna Thakur
SCHOOL HEALTH SERVICES.pptx made by Sapna ThakurSCHOOL HEALTH SERVICES.pptx made by Sapna Thakur
SCHOOL HEALTH SERVICES.pptx made by Sapna Thakur
 
Nutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience ClassNutrition of OCD for my Nutritional Neuroscience Class
Nutrition of OCD for my Nutritional Neuroscience Class
 
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara RajendranMusic Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
Music Therapy's Impact in Palliative Care| IAPCON2024| Dr. Tara Rajendran
 
epilepsy and status epilepticus for undergraduate.pptx
epilepsy and status epilepticus  for undergraduate.pptxepilepsy and status epilepticus  for undergraduate.pptx
epilepsy and status epilepticus for undergraduate.pptx
 
World-Health-Day-2024-My-Health-My-Right.pptx
World-Health-Day-2024-My-Health-My-Right.pptxWorld-Health-Day-2024-My-Health-My-Right.pptx
World-Health-Day-2024-My-Health-My-Right.pptx
 
Presentation on General Anesthetics pdf.
Presentation on General Anesthetics pdf.Presentation on General Anesthetics pdf.
Presentation on General Anesthetics pdf.
 
Big Data Analysis Suggests COVID Vaccination Increases Excess Mortality Of ...
Big Data Analysis Suggests COVID  Vaccination Increases Excess Mortality Of  ...Big Data Analysis Suggests COVID  Vaccination Increases Excess Mortality Of  ...
Big Data Analysis Suggests COVID Vaccination Increases Excess Mortality Of ...
 
METHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaur
METHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaurMETHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaur
METHODS OF ACQUIRING KNOWLEDGE IN NURSING.pptx by navdeep kaur
 
ANEMIA IN PREGNANCY by Dr. Akebom Kidanemariam
ANEMIA IN PREGNANCY by Dr. Akebom KidanemariamANEMIA IN PREGNANCY by Dr. Akebom Kidanemariam
ANEMIA IN PREGNANCY by Dr. Akebom Kidanemariam
 
History and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdfHistory and Development of Pharmacovigilence.pdf
History and Development of Pharmacovigilence.pdf
 
The next social challenge to public health: the information environment.pptx
The next social challenge to public health:  the information environment.pptxThe next social challenge to public health:  the information environment.pptx
The next social challenge to public health: the information environment.pptx
 
Phytochemical Investigation of Drugs PDF.pdf
Phytochemical Investigation of Drugs PDF.pdfPhytochemical Investigation of Drugs PDF.pdf
Phytochemical Investigation of Drugs PDF.pdf
 
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdfMedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
MedDRA-A-Comprehensive-Guide-to-Standardized-Medical-Terminology.pdf
 
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand UniversityCEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
CEHPALOSPORINS.pptx By Harshvardhan Dev Bhoomi Uttarakhand University
 

PPT on Sample Size, Importance of Sample Size,

  • 1. Sample size, importance of sample size, factors influencing sample size and dropouts Naveen K L 2nd Year M Pharmacy (3rd Sem) Dept. of Pharmacology Srinivas College Of Pharmacy Valachil, Mangaluru.
  • 2. Contents: • Introduction • Sample size • Importance of sample size • Selection of sample size • Factors influencing sample size • Dropouts
  • 3. Introduction • Statistics is the science of collection, presentation, analysis and interpretation of numerical data from logical analysis. • Biostatistics is a tool of statistics applied to the numerical data that is derived from biological sciences. • Everything in medical field, biostatistics explains research, diagnosis or treatment which depends on measurement .
  • 4. Sample Size • Number of individuals or the number of observations (a sample) included in the study is referred as sample size. • Main goal of the selection of sample size is to make an inference about population. • The determination of sample size is the act of choosing the number of observation or replicates to include in a statistical sample. • The sample size used in the study is usually determined on the basis of costs, time or convenience of collecting data. (Power, Inverse function of Significance level) Sample Size = (absolute difference)2
  • 6. IMPORTANCE OF SAMPLE SIZE CALCULATION • If the study which is too small is more likely to generate inconclusive, incorrect or spurious results. This is because a smaller sample size will generate or estimates higher variation and these estimates having less useful in modelling and understanding real underlying question of interest in a study. • If the studies are more likely to fail due to inadequate sample size are considered as unethical. This is because exposing human subjects or lab animal to the possible risks associated with research. Additionally, a study having too large faces the ethical problems and will also waste scarce resources such as money, subjects and time.
  • 7. Selection of sample size Study Plan Specify Parameter Choose Effect Size Compute Sample Size
  • 8. Study plan Planning the study involves establishing the purpose of the study What is going to measured to fulfil those purposes What statistical methods and assumption that go into extracting those from your study
  • 9. Cont.. 1)What question/s do you want to answer ? 2)What is the primary outcome of the study ? 3)What kind of the grouping structure will the study have ? 4)What type of hypothesis test will be used ?
  • 10. Specify Parameters • The analysis parameters are assumptions that need to be made about the statistical method to make a sample size justification for the study. • Each study design has different analysis parameters that must be estimated in the design stage of the study. • 2 primary types of parameters used in sample size determination  Prespecified parameters Unknown parameters Eg for parameters are needed for statistical method like Significance level, Standard deviation, intracluster correlation.
  • 11. Choose effect size • Once the analysis parameters are specified then effect of size is important for sample size calculations. • This is the difference in the primary outcome value used in the sample size calculation that the clinical trail or study is designed to reliably detect. • A common parameterisation for the effect of size is the ‘’Standardised effect size’’ • Standardised effect size measures magnitude of treatment effect without units allows more direct and comparable measure of the expected degree of the effect across different studies. • A very common standardised effect size metric is Cohen's effect size. μ1−μ2 / σ
  • 12. • Why is the effect size important in a clinical trail or study ? • 2 main approaches for specifying the effect size  Selection of clinically relevant difference i.e. a difference that would be important from a clinician’s or patient’s Select a realistic difference based on prior evidence and information.
  • 13. Compute SAMPLE SIZE • After successful specifying effect size then compute the sample size or power for the study is done. • Increasing sample size is associated with an increasing in power. (Zα/2+ Zβ)2 × 2σ2 n= (μ1-μ2)2 Where n= required sample size μ1= mean change from baseline in one sample μ2 = mean change from baseline in another sample Z α/2 = standard normal z value for significance level α Zβ = standard normal z value for the power
  • 14. Factors influencing sample size These are the main factors which influences sample size listed as below  Effect of size  The homogeneity  The risk of error  Difference expected  Positive character  Degree of variation among subjects  Level of significance desired- p value  Power of the study desired
  • 15. Dropout • Individual from sample size or from the group of sample which may be rejected from the study because of lack of efficacy. • General formula for calculation of number of dropouts (N) N= cumulative total for 1st dose in series – cumulative total for last dose in series % Dropout rate = (N/Cumulative total for 1st dose in series)×100
  • 16.  Lets consider an Example.... • Vaccination of a population of 120 people • Cumulative total on first dose = 120 • Cumulative total last dose in series = 103 • N = 17 • % Dropout= 14.16
  • 17. References 1. Habib A, Johargy A, Mahmood K, Humma, Design and determination of the sample size in medical research. IOSR-JDMS.2014;13(5):21-31 2. https://www.statsols.com/how-to-use-a-sample-size-calculator retrieved on 21/07/2020 at 03.00 p.m. 3. https://www.scribd.com/doc/98854480/factors-Affecting-Sample-Size retrieved on 22/07/2020 at 10.30 a.m. 4. https://blog.statsols.com/why-is-sample-size-important/?hs_amp=true retrieved on 22/07/2020 at 11.30 a.m. 5. https://youtu.be/Lq5TBf30uFM retrieved on 22/07/2020 at 12.30 a.m. 6. https://www.slideshare.net/mobile/indiandentalacademy/bio-statistics- 61741733 retrieved on 22/07/2020 at 12.14 a.m.