exam 7

What is the main goal of probability sampling in research?

To ensure a representative sample

Larger sample sizes generally reduce sampling error. (True/False)

True

What is the difference between simple random sampling and stratified random sampling?

Simple random sampling gives every individual an equal chance of being selected. Stratified random sampling divides the population into subgroups and selects participants from each subgroup.

Which of the following is an example of descriptive research? a) Testing the effects of sleep deprivation b) Observing study habits of college students c) Conducting a drug trial d) Testing the influence of caffeine on memory

b) Observing study habits of college students

Informed consent is required in all studies involving human participants. (True/False)

False

What are two potential ethical concerns researchers must consider when designing a study?

Informed consent and confidentiality

A positive correlation means: a) As one variable increases, the other decreases b) The two variables are unrelated c) As one variable increases, the other also increases d) As one variable decreases, the other increases

c) As one variable increases, the other also increases

Correlational research can determine the cause of a relationship between two variables. (True/False)

False

Describe the difference between a positive and negative correlation.

A positive correlation means both variables increase together; a negative correlation means as one increases, the other decreases.

What is one key feature of an experiment? a) It always includes a large sample size b) It manipulates at least one independent variable c) It does not require a control group d) It always measures multiple dependent variables

b) It manipulates at least one independent variable

Random assignment is crucial for ensuring that groups are equivalent at the start of an experiment. (True/False)

True

What are the three essential ingredients of an experiment?

Manipulation of the independent variable, random assignment, control of extraneous variables

In a 2x3 factorial design, how many independent variables are there?

2

In a factorial design, interaction effects occur when the effect of one independent variable depends on the level of another independent variable. (True/False)

True

What is the difference between a main effect and an interaction effect?

A main effect is the effect of one independent variable on the dependent variable, while an interaction effect occurs when the effect of one independent variable depends on the level of another.

Which of the following is NOT a potential cost in the cost-benefit analysis conducted by an Institutional Review Board (IRB)?

c) Improvement in future research techniques

Deception in research can never be justified, regardless of the study's potential benefits. (True/False)

False

List two conditions under which researchers can use deception in their studies.

If the study has significant scientific value and the deception does not harm the participants.

What is sampling error?

The difference between the characteristics of the sample and the characteristics of the population from which it was drawn.

What is the main purpose of control groups in experimental research?

Control groups are used to compare results with the experimental group to see if the independent variable had an effect.

What does external validity refer to in an experiment?

The extent to which the results of a study can be generalized to other populations, settings, or times.

Define a within-subjects design in an experiment.

A design in which the same participants are exposed to all levels of the independent variable.

What is internal validity?

The degree to which a researcher can confidently say that changes in the dependent variable were caused by the independent variable.

What is pretest-posttest design?

A design where participants are tested on the dependent variable before and after the experimental manipulation.

What does the term error bars represent in a graph?

Error bars represent confidence intervals, showing the range in which the true population mean is likely to fall.

What is the coefficient of determination (r²)?

The proportion of variance in the dependent variable that is predictable from the independent variable.

In correlational research, what does an r value of -1.00 indicate?

A perfect negative correlation, meaning as one variable increases, the other decreases in a perfectly linear manner.

What are main effects in a factorial design?

The effect of one independent variable on the dependent variable, ignoring other independent variables.

What are interaction effects in a factorial design?

The effect of one independent variable on the dependent variable depends on the level of another independent variable.

What does counterbalancing help control in a within-subjects design?

Counterbalancing helps control for order effects like practice or fatigue effects.

What is placebo effect in an experimental study?

A change in participants' behavior due to their belief that they are receiving a treatment, rather than the treatment itself.

What is the difference between matched random assignment and simple random assignment?

In matched random assignment, participants are first grouped based on a variable, then randomly assigned to conditions, while simple random assignment involves purely random placement.

Define systematic variance.

Variance in a dependent variable that is accounted for by the independent variable.

What is minimal risk in ethical research?

The risk of harm that is no greater than what people ordinarily encounter in daily life.

What is a confederate in experimental research?

A person who is secretly working with the researcher and appears to be a participant or bystander.

What is the main difference between probability and nonprobability samples?

In a probability sample, the researcher can determine the likelihood that a member of the population will be included in the sample, whereas that likelihood cannot be determined in a nonprobability sample.

In which of the following instances might the error of estimation be lowest?

b) The sample is large.

In order to form a simple random sample, you first need a list of all the members in the population. This list is called the:

b) Sampling frame.

I am conducting a study on the effects of standardized testing on third graders in Virginia. Which sampling method am I using?

c) Multistage cluster sampling.

I am interested in investigating why VCU students choose to use the elevator instead of stairs. I survey every 5th student who rides the elevator. Which sampling method am I using?

c) Systematic sampling.

I conduct a study on VCU students, but when describing my results, I state that these findings apply to all emerging adults. Which error am I committing?

c) Misgeneralization.

I want to study aggression in Veterans with combat-related PTSD. I sample only Veterans from the local VA psychiatric clinic. Which best describes my sample?

c) Convenience.

Why are purposive samples generally discouraged in psychological research?

c) They rely on the researcher’s judgment and may not be representative.

In deciding sample size, researchers take ______ into consideration.

d) Power.

Power refers to the likelihood of _________.

d) Detecting effects that really do exist.

The Stall Seat Journal provides statistics about the prevalence of alcohol use among VCU students. This is an example of _____ research.

b) Descriptive.