27th Oct

Question 1

What is a sample?

Answer 1

Collection of data drawn from population

Question 2

What is a target population?

Answer 2

Total finite population we wish to know about from which your sample is drawn

Question 3

What is a study sample?

Answer 3

Participants drawn from target population that constitute data set

Question 4

What is unstratified random sampling?

Answer 4

Every member of target population has same chance of being sampled

Question 5

What is stratified random sampling?

Answer 5

Randomly sample from target population within strata

Every member of each strata has same chance of being sampled

Question 6

Pros and cons of complete sample

Answer 6

Pro: no bias introduced by design
Con: expensive

Question 7

Pros and cons of unstratfied random sampling

Answer 7

Pro: easy to design and conduct
Con: smaller groups may be under-represented by chance

Question 8

Pros and cons of stratified random sampling?

Answer 8

Pro: representative of population, unequal sampling of strata improves power for rare strata
Cons: population may not be easily divisible into strata, strata may not be known til after sampling

Question 9

What is checking?

Answer 9

Checking that sampling is representative

Question 10

What is estimation?

Answer 10

Finding an estimate of some variable of interest
May be by means or frequencies
Usually includes a measure of uncertainty eg a confidence interval or standard error

Question 11

What is hypothesis testing?

Answer 11

Formal statistical testing of a theory
A null hypothesis = no effect
An alternative hypothesis = an effect

Question 12

What is a p value?

Answer 12

Calculate probability of seeing result we have observed or something more extreme if null hypothesis is true

Question 13

What is the cut off for something to be significantly different from the null hypothesis? p=?

Answer 13

p<0.05