Chapter 6 - Sampling - Exam 1

Explain why probability samples are likely to have less sampling error than convenience samples.

Probability samples are chosen such that likelihood of any single individual being selected for the sample is known, because participants are chosen at random from the population or subgroups of the population. Convenience samples are chosen based on who is available and willing to participate in a study. Thus, the probability sample is more likely to represent the population overall and contain less sampling error.

A sample chosen such that the probability of an individual being chosen cannot be determined.

convenience sample

Individuals are selected at random for a study from a list of members of Girl Scout troops to represent the population of girls aged 8 13. What type of sampling is being utilized? a. simple random samples b. stratified random samples c. haphazard/volunteer samples d. cluster samples

d. cluster samples

Which one is not a probability sample? a. simple random sample b. stratified random sample c. cluster sample d. haphazard sample

d. haphazard sample

It is important to use a ________ sample when sampling error is likely to be large. a. convenience sample b. haphazard sample c. volunteer sample d. probability sample

d. probability sample

Which of the following sampling techniques involves choosing individuals from the population at random where the proportions of members of different groups are the same in the population and the sample? a. simple random sample b. cluster sample c. volunteer sample d. stratified random sample

d. stratified random sample

Convenience samples make it more difficult to generalize the results of the study to the population, lowering its

external validity

Which of the following sampling techniques is likely to create the largest amount of sampling error?

volunteer sample

Which of the following describes a quota sample?

60% of the population is left handed; so 60% of the participants chosen are also left handed

What are the advantages and disadvantages of using an internet sample?

Advantages: samples can be more diverse and representative of the population, larger samples can be obtained with fewer resources and few to no restrictions on time or location of data collection, limited bias from interactions with researchers. Disadvantages: may miss subgroups of population who are not web savvy or prefer face-to-face participation, stratified and quota samples are difficult to achieve, difficult to monitor participants while they are completing the study (i.e., may be sources of bias the researcher is unaware of).

All sampling error can be removed from a study if the appropriate sampling technique is used.

FALSE

Internet samples are typically less representative of the population of interest than samples that are collected fact-to-face.

FALSE

It is usually possible to test the entire population in a research study.

FALSE

Volunteer samples are uncommon in psychological research.

FALSE

A disadvantage of cluster sampling is that a portion of the population may be missed in the sample, giving the researcher a sample that is not fully representative of the population.

TRUE

All studies, regardless of sampling technique, are subject to sampling error.

TRUE

External validity of a study should be considered when conclusions are drawn from results collected with a convenience sample.

TRUE

In convenience samples the probability of an individual being chosen from the population cannot be determined, because individuals are not chosen randomly.

TRUE

Many researchers have argued that results from psychological studies using volunteer college students for samples are not informative about the behavior in the general population.

TRUE

Quota samples are similar to stratified random samples without the random selection from subsets of the population.

TRUE

Describe the difference between a sample and a population and how sampling error occurs.

The population is the group of interest, whereas the sample is the group that is tested in the study. The sample is chosen to represent the population in the study. However, differences can occur between data obtained from a sample and data that would be obtained if the entire population had been tested. This difference in data between the population and sample is sampling error.

Which of the following sampling techniques involves choosing individuals from the population such that individuals from the population who volunteer are selected? a. haphazard sample b. quota sample c. simple random sample d. stratified random sample

a. haphazard sample

__________ require access in some way to the entire population to select individuals according to a predetermined probability value. a. probability samples b. haphazard samples c. volunteer samples d. convenience samples

a. probability samples

Individuals are selected at random from a list of phone numbers to be called for a survey. What type of sampling is being utilized? a. simple random samples b. stratified random samples c. haphazard/volunteer samples d. cluster samples

a. simple random samples

An experiment was done to test the hypothesis that exercise affects memory in the elderly. Participants aged 60 & older who responded to an ad in the local paper were recruited for the study. All the participants were presented with the same study list. Then, half of the participants were asked to walk on a treadmill for 20 minutes, while the other half of the participants were asked to complete Sudoku puzzles for 20 minutes. Then, all the participants were given a recognition test for the items in the study list. The treadmill exercise group scored significantly lower on the recognition test than the Sudoku puzzle group. QUESTION #1: What is the most likely population for this study? QUESTION #2: Which sampling technique was used for this study?

all adults over age 60; volunteer sample

Convenience samples are also called:

purposive samples

Unlike a stratified random sample, the _______ sample will make use of convenience sampling techniques such as recruiting participants from a participant sign-up pool or asking students sitting in the library to fill out the survey. a. simple random sample b. quota sample c. volunteer sample d. haphazard sample

b. quota sample

Which of the following sampling techniques is likely to create the smallest amount of sampling error? a. cluster sample b. simple random sample c. volunteer sample d. stratified random sample

b. simple random sample

The most common type of convenience sample used by psychologists is the____________ sample. a. simple random sample b. cluster sample c. volunteer/haphazard sample d. stratified random sample

c. volunteer/haphazard sample

Convenience samples likely increase the amount of sampling error in the study, lowering its

internal validity

Simple random samples can be difficult to obtain for _______populations.

large

Volunteers are selected from students such that the proportion of students in each age range in the sample matches the proportion in the population. What type of sampling is being utilized?

quota samples

Probability samples can ________ the amount of sampling error that exists in a study.

reduce

The percentage of people out of the total number available who respond to a survey is called the:

response rate

The difference in scores that occurs when we test a sample drawn out of the population is:

sampling error

The __________ population is the population to which the researcher wishes to generalize the results of the study.

target