WGU C784 Applied
Question 1
A hospital administrator wants to determine the average length of stay for patients admitted with
pneumonia.
Which measure of central tendency is most affected if one patient remains hospitalized for 120 days
while all others stay fewer than 10 days?
A. Mode
B. Median
C. Mean
D. Range
Correct Answer: C. Mean
,Rationale
The mean includes every observation and is highly influenced by extreme values (outliers). A single
unusually long hospitalization will increase the average considerably. The median is much more
resistant to outliers.
Question 2
Researchers compare blood pressure before and after a new medication in the same group of
patients.
Which statistical test is most appropriate?
A. Independent t-test
B. Paired t-test
C. Chi-square test
D. ANOVA
Correct Answer: B. Paired t-test
Rationale
A paired t-test compares two related measurements collected from the same participants. Because
each patient's blood pressure is measured twice, the observations are dependent.
Question 3
A study reports a p-value of 0.02 using an alpha level of 0.05.
What is the correct interpretation?
A. Accept the null hypothesis.
B. Reject the null hypothesis.
C. The treatment definitely works.
D. The probability the null hypothesis is true is 2%.
Correct Answer: B. Reject the null hypothesis.
Rationale
Since p < α (0.02 < 0.05), there is sufficient evidence to reject the null hypothesis. A p-value does not
indicate the probability that the null hypothesis is true.
,Question 4
Which variable is categorical?
A. Age
B. Blood glucose level
C. Gender
D. Weight
Correct Answer: C. Gender
Rationale
Gender is a categorical (nominal) variable because it represents groups rather than numerical
measurements.
Question 5
Researchers compare smoking status (Yes/No) with lung disease (Present/Absent).
Which statistical test should they use?
A. Chi-square test
B. Paired t-test
C. Pearson correlation
D. Linear regression
Correct Answer: A. Chi-square test
Rationale
The chi-square test evaluates the relationship between two categorical variables.
Question 6
Which graph is best for displaying the distribution of patient ages?
A. Pie chart
B. Histogram
C. Bar chart
D. Scatterplot
Correct Answer: B. Histogram
, Rationale
Histograms display the distribution of continuous numerical data by grouping values into intervals.
Question 7
A confidence interval for a treatment effect is 3.2 to 7.5.
What does this indicate?
A. There is a 95% probability the true value is inside the interval.
B. The interval estimates the plausible range for the population parameter.
C. The treatment effect is exactly 5.35.
D. The sample mean must equal the population mean.
Correct Answer: B. The interval estimates the plausible range for the population parameter.
Rationale
A confidence interval provides a range of plausible values for the true population parameter based on
the sample data.
Question 8
Which correlation coefficient indicates the strongest positive relationship?
A. −0.91
B. 0.12
C. 0.58
D. 0.95
Correct Answer: D. 0.95
Rationale
Correlation coefficients range from −1 to +1. Values closest to +1 indicate the strongest positive linear
relationship.
Question 9
A Type I error occurs when a researcher:
A. Fails to reject a false null hypothesis.
Question 1
A hospital administrator wants to determine the average length of stay for patients admitted with
pneumonia.
Which measure of central tendency is most affected if one patient remains hospitalized for 120 days
while all others stay fewer than 10 days?
A. Mode
B. Median
C. Mean
D. Range
Correct Answer: C. Mean
,Rationale
The mean includes every observation and is highly influenced by extreme values (outliers). A single
unusually long hospitalization will increase the average considerably. The median is much more
resistant to outliers.
Question 2
Researchers compare blood pressure before and after a new medication in the same group of
patients.
Which statistical test is most appropriate?
A. Independent t-test
B. Paired t-test
C. Chi-square test
D. ANOVA
Correct Answer: B. Paired t-test
Rationale
A paired t-test compares two related measurements collected from the same participants. Because
each patient's blood pressure is measured twice, the observations are dependent.
Question 3
A study reports a p-value of 0.02 using an alpha level of 0.05.
What is the correct interpretation?
A. Accept the null hypothesis.
B. Reject the null hypothesis.
C. The treatment definitely works.
D. The probability the null hypothesis is true is 2%.
Correct Answer: B. Reject the null hypothesis.
Rationale
Since p < α (0.02 < 0.05), there is sufficient evidence to reject the null hypothesis. A p-value does not
indicate the probability that the null hypothesis is true.
,Question 4
Which variable is categorical?
A. Age
B. Blood glucose level
C. Gender
D. Weight
Correct Answer: C. Gender
Rationale
Gender is a categorical (nominal) variable because it represents groups rather than numerical
measurements.
Question 5
Researchers compare smoking status (Yes/No) with lung disease (Present/Absent).
Which statistical test should they use?
A. Chi-square test
B. Paired t-test
C. Pearson correlation
D. Linear regression
Correct Answer: A. Chi-square test
Rationale
The chi-square test evaluates the relationship between two categorical variables.
Question 6
Which graph is best for displaying the distribution of patient ages?
A. Pie chart
B. Histogram
C. Bar chart
D. Scatterplot
Correct Answer: B. Histogram
, Rationale
Histograms display the distribution of continuous numerical data by grouping values into intervals.
Question 7
A confidence interval for a treatment effect is 3.2 to 7.5.
What does this indicate?
A. There is a 95% probability the true value is inside the interval.
B. The interval estimates the plausible range for the population parameter.
C. The treatment effect is exactly 5.35.
D. The sample mean must equal the population mean.
Correct Answer: B. The interval estimates the plausible range for the population parameter.
Rationale
A confidence interval provides a range of plausible values for the true population parameter based on
the sample data.
Question 8
Which correlation coefficient indicates the strongest positive relationship?
A. −0.91
B. 0.12
C. 0.58
D. 0.95
Correct Answer: D. 0.95
Rationale
Correlation coefficients range from −1 to +1. Values closest to +1 indicate the strongest positive linear
relationship.
Question 9
A Type I error occurs when a researcher:
A. Fails to reject a false null hypothesis.
