Psychological Statistics Final Examination Study
Guide and Test Bank Master Solution Key
Quantitative Methods, Psychometrics, and Behavioral Research Analysis Manual
1. Which measure of central tendency is most robust against the influence of extreme outliers in a
skewed distribution?
A. Median
B. Mean
C. Mode
D. Variance
Rationale: The median is the middlemost value in an ordered set and is unaffected by
extreme scores, whereas the mean incorporates all numerical values and shifts heavily
toward skewness.
2. In statistical hypothesis testing, what type of error occurs when a researcher rejects a true null
hypothesis (H₀)?
A. Type II error
B. Type I error
C. Standard error
D. Measurement error
Rationale: A Type I error represents a false positive—concluding that an effect or difference
exists when the null hypothesis is actually true in the population.
3. What parametric statistical test is appropriate for comparing the means of two independent
sample groups on a continuous dependent variable?
A. Paired-samples t-test
B. One-way Repeated Measures ANOVA
C. Independent-samples t-test
D. Chi-square test of independence
Rationale: An independent-samples t-test evaluates whether two unrelated groups differ
significantly on a continuous outcome variable.
4. According to the Central Limit Theorem, as sample size (n) increases, what happens to the
, shape of the sampling distribution of the mean?
A. It becomes progressively skewed.
B. It becomes uniform and flat.
C. It matches the shape of the population distribution exactly.
D. It approaches a normal distribution regardless of the population's shape.
Rationale: The Central Limit Theorem states that as sample size increases
(typically n ≥ 30), the sampling distribution of the sample mean approaches
normality regardless of the underlying population distribution shape.
5. What scale of measurement possesses an absolute, non-arbitrary zero point permitting ratio
comparisons between values?
A. Ratio scale
B. Interval scale
C. Ordinal scale
D. Nominal scale
Rationale: A ratio scale has equal intervals and a true zero point representing the complete
absence of the variable (e.g., reaction time in milliseconds).
6. What statistic quantifies the proportion of variance in the dependent variable that is predictable
from the independent variable in a regression model?
A. Pearson correlation coefficient (r)
B. Coefficient of determination (R²)
C. Standard error of the estimate
D. Cronbach's alpha
Rationale: R² measures the percentage of total variation in the dependent variable
explained by the linear predictor(s) in the model.
7. A study yields a p-value of 0.02. Assuming a standard significance level of α = 0.05, what is the
appropriate statistical decision?
A. Fail to reject the null hypothesis
B. Accept the alternative hypothesis as 100% proven
C. Reject the null hypothesis
D. Retain the null hypothesis and recalculate statistical power
Rationale: Because the p-value (0.02) is less than alpha (0.05), the result is statistically
significant, warranting rejection of the null hypothesis.
Guide and Test Bank Master Solution Key
Quantitative Methods, Psychometrics, and Behavioral Research Analysis Manual
1. Which measure of central tendency is most robust against the influence of extreme outliers in a
skewed distribution?
A. Median
B. Mean
C. Mode
D. Variance
Rationale: The median is the middlemost value in an ordered set and is unaffected by
extreme scores, whereas the mean incorporates all numerical values and shifts heavily
toward skewness.
2. In statistical hypothesis testing, what type of error occurs when a researcher rejects a true null
hypothesis (H₀)?
A. Type II error
B. Type I error
C. Standard error
D. Measurement error
Rationale: A Type I error represents a false positive—concluding that an effect or difference
exists when the null hypothesis is actually true in the population.
3. What parametric statistical test is appropriate for comparing the means of two independent
sample groups on a continuous dependent variable?
A. Paired-samples t-test
B. One-way Repeated Measures ANOVA
C. Independent-samples t-test
D. Chi-square test of independence
Rationale: An independent-samples t-test evaluates whether two unrelated groups differ
significantly on a continuous outcome variable.
4. According to the Central Limit Theorem, as sample size (n) increases, what happens to the
, shape of the sampling distribution of the mean?
A. It becomes progressively skewed.
B. It becomes uniform and flat.
C. It matches the shape of the population distribution exactly.
D. It approaches a normal distribution regardless of the population's shape.
Rationale: The Central Limit Theorem states that as sample size increases
(typically n ≥ 30), the sampling distribution of the sample mean approaches
normality regardless of the underlying population distribution shape.
5. What scale of measurement possesses an absolute, non-arbitrary zero point permitting ratio
comparisons between values?
A. Ratio scale
B. Interval scale
C. Ordinal scale
D. Nominal scale
Rationale: A ratio scale has equal intervals and a true zero point representing the complete
absence of the variable (e.g., reaction time in milliseconds).
6. What statistic quantifies the proportion of variance in the dependent variable that is predictable
from the independent variable in a regression model?
A. Pearson correlation coefficient (r)
B. Coefficient of determination (R²)
C. Standard error of the estimate
D. Cronbach's alpha
Rationale: R² measures the percentage of total variation in the dependent variable
explained by the linear predictor(s) in the model.
7. A study yields a p-value of 0.02. Assuming a standard significance level of α = 0.05, what is the
appropriate statistical decision?
A. Fail to reject the null hypothesis
B. Accept the alternative hypothesis as 100% proven
C. Reject the null hypothesis
D. Retain the null hypothesis and recalculate statistical power
Rationale: Because the p-value (0.02) is less than alpha (0.05), the result is statistically
significant, warranting rejection of the null hypothesis.
