AP Statistics: Sampling Methods Review

Simple Random Sample

each individual in a population has an equally likely chance of being chosen

Convenience Sample (Bias)

the individuals in the sample are easily obtained

Cluster sampling

the population is divided into heterogenous clusters and random selection is made within the clusters, or the entire cluster is used.

Example of Voluntary Sampling

A TV show host asks his viewers to visit his website and respond to an online poll.

Example of Stratified sampling

Mrs. Weilacher wants to know the average height of a HH student. She randomly selects 5 students from each grade and finds the average of all their heights.

Example of Convenience sample

A statistics student interviews everyone in his apartment building to determine who owns a cell phone.

A manager associated each employee's name with a number on one ball in a container, shook the container up, then drew balls without looking to select a sample of 555 employees. A.Simple Random Sample B. Stratified Sample C. Cluster Sample D.Systematic Sampling E. None of the above

A. It is simple random sample since each member receives a number first.

In order to survey the opinions of its customers, a restaurant chain obtained a random sample of 30 customers from each restaurant in the chain. Each selected customer was asked to fill out a survey. Which one of the following sampling plans was used in this survey? A. Cluster Sampling B. Stratified Sampling C. Systematic Sampling D. Simple Random Sampling E. Convenience Sampling

B Since the customers we divided by chain first then they are stratified.

A school chooses 33 randomly selected athletes from each of its sports teams to participate in a survey about athletics at the school. A. Simple Random Sample B. Stratified Sample C. Cluster Sample D. Systematic Sampling E. Convenience Sampling

B. Since they are breaking up the athletes into teams then it is stratified by teams to choose the sample.

A principal orders t-shirts and wants to check some of them to make sure they were printed properly. She randomly selects 2 of the 10 boxes of shirts and checks every shirt in those 2 boxes. A. Simple Random Sample B. Stratified Sample C. Cluster Sample D. Systematic Sampling E. Convenience Sampling

C. Since she is choosing 2 boxes but sampling all the shirts in those boxes

A restaurant leaves comment cards on all of its tables to learn about customer satisfaction. Each comment card is a brief survey that customers can fill out if they choose to. A. Simple Random Sample B. Stratified Sample C. Cluster Sample D. Systematic Sampling E. Voluntary Response

E. Only people who want to will return the card

A politician asks his neighbors their opinions about a controversial issue. A. Simple Random Sample B. Stratified Sample C. Cluster Sample D. Systematic Sampling E. Convenience Sampling

E. Since he asks the people around him then he is conveniently asking his sample

Example of Systematic sampling

Every fifth adult entering an airport is checked for extra security screening.

Example of Cluster sampling

Mrs. Weilacher wants to know the average height of a HH student. She randomly selects 5 classrooms and finds the average height of all kids in those 5 rooms.

Example of multistage sampling

Mrs. Weilacher wants to know the average height of a HH student. She randomly selects 5 classrooms then samples every 3rd student in each of those classrooms.

Example of Simple Random sample

The names of 100 employees are written on 100 cards. the cards are placed in a bag, mixed well, and three names are picked from the bag.

Systematic Sample

Obtained by selecting every 10th (or 15th etc..) individual from the population

Stratified sampling

The population being used is divided into groups characterized by a common trait and then the sample has a representation of each group in the sample. For example, ensuring that various age brackets, genders, backgrounds and religions are used in the research.

Voluntary Sampling

The researcher invites members of the population to participate in the survey on a voluntary basis.

multistage sampling

select from successively smaller groups within the population in stages