BAPSY Psychological Research and Statistics 3 — Questions and Answers
Question 1: In which research design does the researcher manipulate one variable while holding all others constant to establish causation?
- Correlational study
- Case study
- True experiment (Correct answer)
- Cross-sectional survey
Correct answer: True experiment
True experiments with random assignment and manipulation of the independent variable are the gold standard for establishing causal relationships.
Question 2: The mode is the preferred measure of central tendency when data are:
- Normally distributed and continuous
- Ratio scale and skewed
- Nominal (categorical) (Correct answer)
- Ordinal with many tied ranks
Correct answer: Nominal (categorical)
The mode is the only measure of central tendency applicable to nominal data because mean and median require at least ordinal measurement.
Question 3: A researcher uses debriefing after a deception study. What is the PRIMARY ethical purpose?
- To collect additional data from participants
- To satisfy IRB reporting requirements
- To restore participant understanding and well-being after deception (Correct answer)
- To test whether the manipulation was successful
Correct answer: To restore participant understanding and well-being after deception
Debriefing serves to inform participants of the true purpose, remove any false impressions, and address any distress caused by deception.
Question 4: Which nonparametric test is the appropriate alternative to a one-sample t-test when normality cannot be assumed?
- Mann-Whitney U test
- Wilcoxon signed-rank test (Correct answer)
- Kruskal-Wallis test
- Friedman test
Correct answer: Wilcoxon signed-rank test
The Wilcoxon signed-rank test compares a single sample's median to a hypothesized value without assuming normality.
Question 5: Demand characteristics in an experiment refer to cues that:
- Increase the difficulty of experimental tasks
- Lead participants to guess the study's purpose and alter their behavior accordingly (Correct answer)
- Reduce the reliability of the dependent variable
- Create social desirability bias only in survey research
Correct answer: Lead participants to guess the study's purpose and alter their behavior accordingly
Demand characteristics are cues in the experimental setting that suggest the expected behavior, potentially inflating or distorting results.
Question 6: When a distribution has a positive skew, the typical order of measures of central tendency is:
- Mean < Median < Mode
- Mode < Median < Mean (Correct answer)
- Median < Mode < Mean
- Mean = Median = Mode
Correct answer: Mode < Median < Mean
In a positively skewed distribution, the tail pulls the mean highest, followed by the median, with the mode at the peak (lowest of the three).
Question 7: A within-subjects design reduces error variance primarily by:
- Increasing the number of independent variables
- Removing individual difference variance from the error term (Correct answer)
- Eliminating all demand characteristics
- Randomly assigning participants to conditions
Correct answer: Removing individual difference variance from the error term
Because the same participants appear in all conditions, stable individual differences are partitioned out, reducing unexplained (error) variance.
BAPSY Psychological Research and Statistics 3
In which research design does the researcher manipulate one variable while holding all others constant to establish causation?