sampling

Question 1

what is sampling

Answer 1

the process of selecting a smaller groups from a larger group to study the characteristics of the larger group

Question 2

sampling used to

Answer 2

make predictions or generalisations about the whole population

Question 3

population

Answer 3

larger group

Question 4

sample

Answer 4

subset of the population selected to represent the whole group

Question 5

representativeness

Answer 5

sample should accurately represent the population it cannot be biased

Question 6

random selection

Answer 6

each member should have and equal chance of being selected

Question 7

sufficient sample size

Answer 7

larger samples reduce random error making estimates more precise

Question 8

central limit theorem

Answer 8

sample size of 30 is often sufficient for the sampling distribution of the mean to approximate normality

Question 9

simple random sampling

Answer 9

number assigned to each member in sampling frame and number randomly generated

Question 10

characteristics of simple random sampling

Answer 10

easy to implement and provide unbiased estimate but not feasible for large populations and chance of sampling error

Question 11

stratified sampling

Answer 11

population divided into groups based on characteristics and number from each group is selected randomly

Question 12

characteristics of stratified sampling

Answer 12

accurate but requires knowledge about the population and may not be feasible if population has many strata

Question 13

systematic random sampling

Answer 13

population is selected at regular intervals

Question 14

characteristics of systematic random sampling

Answer 14

easy to implement, more efficient and useful when population is already ordered but chance of bias and not appropriate if population doesn’t follow natural order

Question 15

cluster sampling

Answer 15

sample of clusters selected randomly, and survey everyone in selected clusters or take sample from each cluster

Question 16

characteristics of cluster sampling

Answer 16

cost effective and useful when difficult to obtain a list of individuals but less precision and requires larger sample sizes

Question 17

sampling error

Answer 17

difference between sample mean and population mean due to random variation in the sampling process

Question 18

sampling error occurs

Answer 18

when studying a subset of the population

Question 19

standard error

Answer 19

measures expected variation due to sampling error

Question 20

standard error is crucial

Answer 20

for hypothesis testing to calculate confidence intervals and test statistics