1.3 Collecting Sampling Data

Greyhound Lines randomly selects 100 busses during a certain week and surveys all passengers on the busses. Which type of sampling is​ used?

Cluster Sampling

Convenience Sampling

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.

Observational Study

In an observational​ study, the researchers observe and measure specific​ characteristics, but they​ don't attempt to modify the subjects being studied

Experiment

In an​ experiment, the researchers apply some treatment and then proceed to observe its effects on the subjects.

Which of the following corresponds to the case when every sample of size n has the same chance of being​ chosen?

Simple Random Sample

To estimate the percentage of defects in a recent manufacturing​ batch, a quality control manager at General Foods selects every 20th soup can that comes off the assembly line starting with the third until she obtains a sample of 150 soup cans.

Stratified Sampling

Which sampling method subdivides the population into categories sharing similar characteristics and then selects a sample from each​ subdivision?

Stratified sampling method involves subdividing the population and uses a sample of members from each subdivision of the population.

A study is conducted to measure​ children's growth rates without any treatment applied to the children. What best classifies this​ study?

observational Study

In a poll conducted by a certain research​ center, 1151 adults were called after their telephone numbers were randomly generated by a​ computer, and 95 % were able to correctly identify the attorney general. Which type of sampling did the research center​ use?

Random Sampling

Cluster Sampling

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.

Which sampling method divides the population up into​ sections, randomly selects some of those​ sections, then chooses all the members from the selected sections to​ study?

Cluster sampling involves subdividing the population and using all members from a randomly selected group of subdivisions.

A magazine asks its readers to call in their opinion regarding the quality of the articles. Which type of sampling is​ used?

Convenience Sampling

A man is selected by a marketing company to participate in a paid focus group. The company says that the man was selected because his name is among the first 400 in the phone number listings. Which type of sampling did the marketing company​ use?

Convenience sampling

Random Sampling

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.

​_______ is used when subjects are assigned to different groups through a process of random selection.

Randomization is used when subjects are assigned to different groups through a process of random selection. The logic behind randomization is to use chance as a way to create two groups that are similar. Although it might seem that we should not leave anything to chance in​ experiments, randomization has been found to be an extremely effective method for assigning subjects to groups.

Stratified Sampling

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.

Systematic Sampling

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.