SAMPLING
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SAMPLING When you want to select a sample from a large number. For example, select 50 people from a list of 400 people. There are many methods to take a sample. For GCSE maths, you need to know about: –Simple random sampling. –Stratified random sampling.
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SAMPLING. When you want to select a sample from a large number. For example, select 50 people from a list of 400 people. There are many methods to take a sample. For GCSE maths, you need to know about: Simple random sampling. Stratified random sampling. SIMPLE RANDOM SAMPLING. - PowerPoint PPT Presentation
Transcript of SAMPLING
SAMPLINGWhen you want to select a sample from a large number.
For example, select 50 people from a list of 400 people.
There are many methods to take a sample.
For GCSE maths, you need to know about:
–Simple random sampling.
–Stratified random sampling.
SIMPLE RANDOM SAMPLING
Everything has an equal chance of being included in the sample.• Give everything a number.• Use a random number table or a calculator to select the sample.
Example: From 758 students (numbered 1 to 758), select 15 students.
191, 842, 347, 182, 103, 597, ……
OR use RAN# on your scientific calculator.
STRATIFIED RANDOM SAMPLING
Everything is put into categories first. (gender, age groups, year group,…)
A sample is chosen from each category in the same proportion to the whole population.
Example: A sample of 50 students is to be taken.How many pupils would you select from each year group?
Year 7 162
Year 8 161
Year 9 157
Year 10 63
Year 11 58
TOTAL = 601
