Question

Identify the type of sampling used.

1) to determine the prevalence of human growth hormone (HGH) use among high school varsity basball players, the state athletic commission randomly selects 50 high schools. all members of the selected high schools"s varsity baseball teams are tested for HGH.

2) to determine customer opinion of its boarding policy, southwest airlines randomly selects 60 flights during a certain week and surverys all passengers on the flights

3) a member of congress wishes to determine her constituency's opinion regarding estate taxes, she divides her constituency into three income classes: low income households, middle income households, and upper income households, she then takes a simple random sample of households from each class

Answer 1

1) Cluster Sampling:

In cluster sampling , first we select the clusters randomly and then study on all the elements of the selected clusters.

Here all the high school are the clustters and we slect 50 high school from all the school randomly ,

and the study all the members of the selected high schools"s varsity baseball teams are tested for

HGH.

2) Cluster Sampling.

Here clusters are "all the flights during a certain week". Then select 60 clusters ( flights ) randomly and then study all the passengers on the flights.

3) Stratified Sampling

In stratified sampling we first make homogeneous groups called them "strata" on the basis of some characteristics and then select random sample from all the groups. Next we collec the information from the selected elements from all the strata. This technique of selecting elements is called stratified sampling.

Here the whole of the study population is divided on the basis of the income level into three grous as

low income households, middle income households, and upper income households, and then select some household from each groups randomly. Then study on the selected household. So it is a stratified sample and the technique used for selection is called stratified sampling.