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Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
Presentation sampling
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Presentation sampling

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    • 1. EDU 702 :Research Methodology Sampling Adibah Halilah bt Abdul Mutalib 1
    • 2. Topic areas:Definition• Population• SampleIdentify & Contrast• Target and Accessible population• Random Sampling and Non-RandomRandom Sampling• Types of Random Sampling.• How to select a random sample. 2
    • 3. Problem : Relationship between stresslevels and smoking among university students 3
    • 4. Research question : You would like to know the number ofcigarettes the average university students smokes Population of all university students in Malaysia = 12,000 Population of university students in UITM = 4,000 Population of male students = 1,400 10% Populations of UITM first year male students = 140 4
    • 5. Definition of a Sample • A small group of people studied to collect informationSample to draw conclusion about the larger group • Process of selecting the people (individuals) to beSampling observed ( studied) 5
    • 6. Example of sample within a population Sample: information obtained Population: results of studies applied here 70 700 6
    • 7. Questions: Can a Sample & Population have the same groups of people? Smokers at University All smokers Sample – Year 1 university students who are smokers Population – Smokers at University 7
    • 8. Discussion: How to select Sample? Effects of eating “Nasi Lemak” for breakfast on young students. Teachers view about teaching Math and Science in Bahasa Malaysia. Students addiction to computer games and poor grades. 8
    • 9. How to define the populationStage 1: Define the population• Who can you administer the results to?• Any size• Need to have at least one characteristic different from other populationStage 2 : Identify “Who” or“What”• Educator• Object 9
    • 10. TARGET vs. ACCESSIBLE POPULATION • Ideal group/actual group TARGET researchers like to generalize • Rarely available • Those who researchers areACCESSIBLE able to generalize • Actual choice 10
    • 11. Advantages of defining & narrowing populationMoney Time Effort 11
    • 12. Random vs. Non-random-SamplingRandom Non-Sampling (Purposive) All have equal and Chosen based on a criteriaindependent chanceSelects a representative of No equal chancepopulation Should be large and random Some have no chance at all No bias Some types show biasness 12
    • 13. Random Sampling Methods(A) Simple Random Sampling(B) Stratified Random Sampling(C) Cluster Random Sampling(D) Two-stage Random Sampling 13
    • 14. (A) Simple Random Sampling ( 1 of 2)• Each individual has equal and independent chance of selection• The larger the sample, the more it represents the population• Any differences is not due to biasness 14
    • 15. Simple Random Sampling (2 of 2)• Method of finding individuals : Use a table of Choose any Read the numbers random numbers number on the to select your ( statistic book) column sample 15
    • 16. Using the Table of Random Numbers• Step 1: Select column of numbers• Step 2: Choose any number on the column• Step 3: Read the first 4 digits ( if you have population of 4 digits)• Step 4: Pick out numbers and write them down. 16
    • 17. Exercise: Select the first 30 numbers for a population of 300. Column 1 Column 2 Column 3 Column 4 099922 231100 182203 012030 122331 334444 092010 231102 644632 088765 001220 120301 162311 755664 005440 909201 234577 112344 194020 718291 344666 412346 230440 503813 092303 080902 210490 120311 009330 006102 530209 301020 230420 003233 409201 015663 17
    • 18. Answer:• Looking at column 1: – Selected individuals are : • 099 • 122 • 644 • 162 • 234 • 344 • 092 • 009 • 230 18
    • 19. (B) Stratified Random Sampling• Certain ‘strata’ selected• Sample in same proportion as they exist in the population• Advantages: Increases likelihood of representativeness 19
    • 20. Calculating Stratified Random Sampling• Step 1: Identify the target ( accessible) population• Step 2: Select the ratio of their relationship• Step 3: Determine the % of target population used as sample• Step 4: Calculate the % sample for each strata• Step 5: Use Table of random numbers to find the individuals in the respective strata 20
    • 21. Select gender individuals as they exist in the population ( 365)Female Male• 60 % • 40%• 60 % of 365 = 219 • 40 % of 365 = 146 Therefore, Female : Male 60 : 40 219 : 146 Now, select 40 % of each strata as you representative… Female : Male 88 : 58 21
    • 22. (C ) Cluster Random Sampling• Ideal to include certain groups/ cluster• However at times it is not possible to select individual due to • Time • Effort• Select individuals based on ( not individuals) • Groups • Clusters • Subjects 22
    • 23. All Year 6 students in Selangor Selected schools chosen as clusters 1 2 6 5 9 3 8 7 11 1 4 10 12 13 23
    • 24. Cluster random sampling… Advantages Disadvantages 24
    • 25. Common mistake made with Cluster random sampling.• Randomly selecting only one cluster as a sample and choosing to interview/ survey all• Cluster must be randomly selected not individuals 25
    • 26. (D) Two-stage Random Sampling• Combination of Cluster random sampling and individual random sampling – First select clusters randomly – Then select students randomly from the clusters. NH KJ XT FD XT PO PO P, T, S AB RS RS 26
    • 27. Thank you… 27

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