Sampling

Types of Sampling

There are five types of sampling: Random, Systematic, Convenience, Cluster, and Stratified.

• Random sampling is analogous to putting everyone's name into a hat and drawing out several names. Each element in the population has an equal chance of occurring. While this is the preferred way of sampling, it is often difficult to do. It requires that a complete list of every element in the population be obtained. Computer generated lists are often used with random sampling. You can generate random numbers using the TI82 calculator.
• Systematic sampling is easier to do than random sampling. In systematic sampling, the list of elements is "counted off". That is, every kth element is taken. This is similar to lining everyone up and numbering off "1,2,3,4; 1,2,3,4; etc". When done numbering, all people numbered 4 would be used.
• Convenience sampling is very easy to do, but it's probably the worst technique to use. In convenience sampling, readily available data is used. That is, the first people the surveyor runs into.
• Cluster sampling is accomplished by dividing the population into groups -- usually geographically. These groups are called clusters or blocks. The clusters are randomly selected, and each element in the selected clusters are used.
• Stratified sampling also divides the population into groups called strata. However, this time it is by some characteristic, not geographically. For instance, the population might be separated into males and females. A sample is taken from each of these strata using either random, systematic, or convenience sampling.

1. Each of the entries into a contest are placed into a hat. Five entries are drawn from the hat to choose the winners.

1.   ?    Stratified
2.   ?    Systematic
3.   ?    Cluster
4.   ?    Simple Random Sample
5.   ?    Convenience

2. A teacher numbers the students in the class by fours and then asks every person assigned the number 3 how much time they spend studying.

1.   ?    Stratified
2.   ?    Simple Random Sample
3.   ?    Convenience
4.   ?    Cluster
5.   ?    Systematic

3. An environmental biologist is taking an inventory of the plant life in a forest. She divides a section of the forest into 2m x 2m plots, randomly selects 5 plots, and then counts the number of each type of plant that occurs in those plots.

1.   ?    Systematic
2.   ?    Cluster
3.   ?    Stratified
4.   ?    Convenience
5.   ?    Simple Random Sample

4. A student is required to interview at least three faculty members to determine their opinion on the Farm Progress Show coming to Decatur. The student randomly selects three names from a list of the full time faculty and then asks those faculty members.

1.   ?    Cluster
2.   ?    Convenience
3.   ?    Systematic
4.   ?    Stratified
5.   ?    Simple Random Sample

5. A teacher takes the names of all of her students, puts them into a spreadsheet, and randomly picks 20 female students and 10 male students to ask how much time they're spending studying.

1.   ?    Stratified
2.   ?    Convenience
3.   ?    Simple Random Sample
4.   ?    Cluster
5.   ?    Systematic

 

 

 

6. A student is required to interview at least three faculty members to determine their opinion on the Farm Progress Show coming to Decatur. The student randomly selects one of the office complexes on campus and asks all faculty in that complex their opinion.

1.   ?    Cluster
2.   ?    Systematic
3.   ?    Stratified
4.   ?    Simple Random Sample
5.   ?    Convenience

 

7. The entries to a contest are arranged by the age group of the submitter. Five winning entries are selected from those under age 20, ten from those age 20 to 40, and five from those over age 40.

1.   ?    Systematic
2.   ?    Cluster
3.   ?    Stratified
4.   ?    Convenience
5.   ?    Simple Random Sample

 

8. A student is required to interview at least three faculty members to determine their opinion on the Farm Progress Show coming to Decatur. The student emails every faculty member to ask them and uses the first three responses.

1.   ?    Cluster
2.   ?    Stratified
3.   ?    Convenience
4.   ?    Systematic
5.   ?    Simple Random Sample

 

9.  A student is required to interview at least three faculty members to determine their opinion on the Farm Progress Show coming to Decatur. The student randomly selects one of the office complexes on campus and asks all faculty who are in their offices their opinion.

1.   ?    Simple Random Sample
2.   ?    Stratified
3.   ?    Systematic
4.   ?    Convenience
5.   ?    Cluster

 

10.  Each of the entries into a contest are placed into a hat. Five entries are drawn from the hat to choose the winners.

1.   ?    Cluster
2.   ?    Convenience
3.   ?    Simple Random Sample
4.   ?    Stratified
5.   ?    Systematic