Psychlearn 6 - Sampling and external validity

In which of the following situations would probability sampling be appropriate?

When the population is large but can be broken into smaller groups that can then be sampled randomly or systematically.

A cognitive scientist is interested in applying the findings of his memory study to all adult learners in the United States. He decides to use the student research participant pool at his university for his sample because they are easily accessible. This is an example of

Convenience sampling.

Which of these sampling methods do not yield data that generalizes to the larger population?

Convenience sampling.

Dr. Padilla wants to measure attitudes related to scientific productivity among attendees at a national conference on higher education. To narrow the sampling frame, Dr. Padilla divides the participant list into regions of the country and randomly selects two states from each region. She then divides each state list into public and private universities and randomly selects two universities from each state. Finally, Dr. Padilla selects 50 participants randomly from this narrowed list. This type of sampling would be considered

Multistage.

If a sampling frame is not available, a researcher can use

Nonprobability sampling. Convenience sampling.

In which of the following situations would nonprobability sampling be appropriate?

Participants are chosen by their accessibility, making it fairly easy to acquire a sample. When recruiting participants from a population that might be difficult to access, the researcher depends upon the first participants to ask their own contacts to also participate. When the size and compilation of the population is not clearly defined.

A researcher uses a nonprobability technique to recruit participants, taking steps to ensure that important subgroups are represented proportionally in the sample. The nonprobability sampling opens the sample to biases. This technique is known as

Quota sampling.

A research methods instructor wants to investigate the influence of active learning techniques on student motivation for students in her class this semester, which is the population of interest. She enters the ID numbers of the 150 students in her class into a random number generator and then selects 35 students to participant in an active learning activity and follow-up questionnaire. The researcher used

Simple random sampling.

A researcher wants to know how often U.S. high school students engage in physical activity during their free time. She asks the athletic office at the local high school for a list of all the students who are on the school's sports team so she can randomly select participants from this list. Her population of interest is U.S. high school students. What is the group from which her sample is actually drawn?

Students at this high school who are on the school's sports teams.

In snowball sampling, who does the researcher ask to recommend additional participants?

Study participants.

This approach can be used to make certain that sampling occurs throughout the entire sampling frame. This approach does not require a random numbers table or generator, but relies on selecting individuals that have a specific placement in the sampling frame.

Systematic sampling.

A researcher was interested in the relationship between multitasking during class and memory for the material discussed during that class. After recruiting 35 college students, she decided to observe the participants' multitasking behaviors during class in a large lecture hall, and then asked them to take a short quiz on the material from that day's class session. The level of authenticity for this study would be

high, since the multitasking observed should reflect a typical class situation.

To evaluate the strength of a study's external validity, you should examine the:

level of authenticity of the research methodology. population of interest and the sampling method. type of claim made by the researchers.

The population of interest for a research study is adolescents in the United States aged 13-15. The researcher recruits 50 participants from a local junior high and high school and sets up a laboratory experiment to examine the influence of peers on learning tasks. The researcher takes care only to manipulate the independent variable and holds all other variables constant. In this example, the researcher has minimized

population validity to maximize internal validity.

If a researcher wishes to study a population that is hard to locate then which of these is generally the preferred method of sampling?

Snowball sampling.

Which research design has the highest population validity for a study whose population of interest is students enrolled at a certain university?

Ask the registrar for a list of all the students enrolled at the university and randomly select participants.

Which of these claims has the strongest external validity?

Heart rate increases when adrenaline production increases.

If a researcher takes care to ensure a high level of generalizability in a study, which type of validity could be limited as a result?

Internal validity.

Which of the claims listed below would have a high degree of generalizability?

Reaction time in a visual selection task decreases (becomes faster) with age. The type of memory, implicit or explicit, affects the way information is stored in the brain.

Why is a master list of all members of the population important to probability sampling?

To avoid selection bias when sampling.

Why would a researcher choose to conduct a study in a laboratory setting instead of a real-world setting?

To maximize internal validity.

A study that lacks external validity

has a low degree of generalizability. can still represent high-quality research.

A developmental psychology researcher wanted to study sharing among preschool children in her laboratory. When the children entered the lab, however, they were nervous and much more timid than they were at home or in their preschool classroom. In this case the study's setting

has low authenticity.

When trying to decide whether to conduct a study in a laboratory setting or a real-world setting, a researcher should consider the

importance of authenticity. importance of internal validity.

A research claim about gender attitudes among workers at a local company would be considered

not generalizable.

A researcher conducted a study with 1-year-old children to measure the influence of an adult model versus a child model on imitation in toddlers. To strengthen external validity of study, the researcher could

replicate the study with a group of toddlers who are 2-years-old.

A researcher knew that her findings would only generalize to the patients at her private clinic. This knowledge is important

so the findings are not generalized beyond the strength of their external validity.