This document discusses sample size calculation and provides formulas for determining appropriate sample sizes for different types of studies. It explains that sampling involves studying a subset of a population to make inferences about the whole population. The key types of studies covered are: 1) calculating a proportion, 2) calculating the difference between two proportions, 3) calculating a mean, and 4) calculating the difference between two means. Formulas for determining sample sizes for each of these study types are presented along with examples and exercises to demonstrate how to apply the formulas.
An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called study and control groups to receive and not receive an experimental preventive or therapetuic procedure, maneuver, or intervention .
Study designs, Epidemiological study design, Types of studiesDr Lipilekha Patnaik
Study design, Epidemiological study designA study design is a specific plan or protocol
for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one.
An epidemiological experiment in which subjects in a population are randomly allocated into groups, usually called study and control groups to receive and not receive an experimental preventive or therapetuic procedure, maneuver, or intervention .
Study designs, Epidemiological study design, Types of studiesDr Lipilekha Patnaik
Study design, Epidemiological study designA study design is a specific plan or protocol
for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one.
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
The STUDY of the DISTRIBUTION and DETERMINANTS of HEALTH-RELATED STATES in specified POPULATIONS, and the application of this study to CONTROL of health problems."
Taming the ever-evolving Compliance Beast : Lessons learnt at LinkedIn [Strat...Shirshanka Das
Just when you think you have your Kafka and Hadoop clusters set up and humming and you’re well on your path to democratizing data, you realize that you now have a very different set of challenges to solve. You want to provide unfettered access to data to your data scientists, but at the same time, you need to preserve the privacy of your members, who have entrusted you with their data.
Shirshanka Das and Tushar Shanbhag outline the path LinkedIn has taken to protect member privacy in its scalable distributed data ecosystem built around Kafka and Hadoop.
They also discuss three foundational building blocks for scalable data management that can meet data compliance regulations: a centralized metadata system, a standardized data lifecycle management platform, and a unified data access layer. Some of these systems are open source and can be of use to companies that are in a similar situation. Along the way, they also look to the future—specifically, to the General Data Protection Regulation, which comes into effect in 2018—and outline LinkedIn’s plans for addressing those requirements.
But technology is just part of the solution. Shirshanka and Tushar also share the culture and process change they’ve seen happen at the company and the lessons they’ve learned about sustainable process and governance.
A sample design is a definite plan for obtaining a sample from a given population. Researcher must select/prepare a sample design which should be reliable and appropriate for his research study.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
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ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
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TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
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Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
1. Sample Size Calculation
Dr P Raghavendra
2nd Year Post-Graduate
Dept of Community Medicine,
Siddhartha Medical College, Vijayawada
2. What is Sampling?
• A sample is a part of the population under
study.
• In most situations, it might not be possible to
study an entire population.
• We typically draw a subset of people drawn
from a larger population and then use
inferential statistics to make an inference from
the sample and apply it to the whole
population.
3. What is sampling?
• We try to study the characters of the
population by measuring them from a smaller
number of subjects.
• Sample is expected to be the MIRROR of the
population.
• Cook sees only a handful of rice to check if it is
cooked or not.
4. Attributes of a good sample
To extrapolate the inference of the sample to
the population, the sample should be:
• A representative of the population.
• Should be large enough.
5. If sample is too large…
Good precision
Less errors
Less bias
But,
Wastage of time, money and resources
Resources could be as well be deviated to
other projects.
Not cost-effective
6. If sample is too small…
Inaccurate results.
More source of bias.
Power of the study comes down.
Study fails to give meaningful information.
Waste of resources on a inaccurate study.
Ethical issues about recruiting patients into a
meaningless study.
8. How big should a sample be?
• Formulae are present.
• The forthcoming formulae are tailor-made for
a power of 80% and a Confidence Interval of
95%. (Acceptable levels)
• Power of the study is the ability to detect the
true significance.
• 95% CI means 5% of erroneous significance.
9. Types of studies
• Based on what we are measuring, there are 4
types of studies:
1. Calculating the proportion
Qualitative
2. Calculating the difference of
proportions
3. Calculating the mean
Quantitative
4.Calculating the difference in means
10. Qualitative v/s Quantitative
• Qualitative are those which can be answered
as YES or NO, Male or Female, etc.
• We can only measure their numbers,
eg: Number of males, Number of MDR-TB
cases among TB patients, etc.
• A set of qualitative data can be expressed as
proportions. Eg: Prevalence, success rate.
11. Qualitative v/s Quantitative
• Quantitative are those which can be measured
in numbers, like Blood pressure, Age, etc.
• A set of quantitative date can be expressed in
mean and its standard deviation.
• Mean is the average of all variables in the
data.
• Standard deviation is a measure of the
distribution of variables around the mean.
12. 1. Calculating Proportion
• This is used in cases where we are trying to
find proportions.
• Eg: for studies like:-
– Estimation of prevalence of tuberculosis in
Vijayawada city in 2012.
– Prevalence of malignant hyperthermia as a
complication of enflurane administration.
13. 1. Calculating Proportion
N= 4PQ/d 2
Where,
• P = Prevalence (from previous studies)
• Q = 100 – P
• d = allowable error (5-20% of P)
14. Exercise - 1
• Calculate the sample size required to find out
the proportion of children receiving BCG
vaccination if the BCG coverage of that area in
previous studies was 80%.
• Sol: P = 80; Q = 100-P = 20; d= 20% 0f P = 16.
N= 4PQ/d2
= 4x80x20
16x16
= 25
15. 2. Calculating Difference in proportion
• This is used when we measure the significance
of difference between two proportions.
• Eg: For studies like:-
– Diagnostic supremacy of CT Chest v/s X-ray chest
in pulmonary tuberculosis.
– Success rate of Streptomycin v/s Kanamycin in
cure of MDR-TB
16. 2. Calculating Difference in proportion
N= 15.7 x x Q
(P1-P2 )2
Where,
• P1 and P2 are the proportions of the 2 groups
• is the average of P1 and P2
• Q is 100 -
17. Exercise - 2
• A new treatment regimen for Tuberculosis was
planned. The success rates of DOTS was 75%.
The success rate of the new treatment in a
pilot study was 85%. Calculate the sample size
for a study to compare the success rates of the
two regimen.
Hint: N= 15.7 x x Q
(P1-P2 )2
18. Solution to exercise - 2
Here, P1 = 75; P2 = 85%; = 80
Q = 100 - = 20; P1-P2 = 10
Hence N = (15.7 x 80 x 20) / (10 x 10)
= 251
19. 3. Calculating the mean
• This formula is used in quantitative studies
where we are estimating the mean of the
study group.
• Eg: For studies like:-
– Estimation of mean age at diagnosis of
tuberculosis in Vijayawada city
– Bacteriological index at the initiation of DOTS in
TB patients attending DOTS centre of
GGH, Vijayawada
– Mean time of onset of action of Sevoflurane
20. 3. Calculating the mean
N= 4 2/d2
Where,
• (Sigma) is the Standard deviation as in
similar studies done previously
• d = allowable error (5-20% of )
21. Exercise - 3
• We are planning to do a study regarding Age
of onset of smoking practice among youth in
rural Vijayawada. A previous such study done
in Andhra Pradesh gave a mean age at onset
as 25 years with a standard deviation of 10
years. Calculate the sample size required to do
the planned study.
Hint: N= 4 2/d2
22. Solution to exercise - 3
Here, = 10.
So, d = 20% of = 2.
Hence, N = (4 x 10x10) / (2 x 2)
= 100
23. 4. Calculating Difference in Means
• This is used in studies where we are
calculating the difference achieved
quantitatively during the study.
• Eg: For studies like:-
– Average weight gain in patients of tuberculosis
before and after DOTS.
– Mean fall in Blood pressure due to propofol
infusion.
24. 4. Calculating Difference in Means
N = 15.7 ( x 2
1 2)/d
Where,
• 1 and 2 are the standard deviations of the 2
study groups,
• d is the smallest meaningful difference that
can be measured.
In before-after type of studies, 1 = 2 =
25. Exercise - 4
• Determine the sample size required to detect
an increase of 10 cells/cu.mm in CD4 counts of
HIV patients those receiving HAART, assuming
the standard deviation of CD4 counts to be 70
cells/cu.mm.
Hint: N = 15.7 ( 1x 2)/d2
26. Solution to exercise - 4
Here, 1 = 2 = 70, d = 10
N = (15.7 x 70 x 70) / (10 x 10)
= 769