EAP Interpreting Academic Data 4 — Questions and Answers
Question 1: A research article states that the effect size (Cohen's d) is 0.85. How is this generally interpreted?
- Small effect
- Medium effect
- Large effect (Correct answer)
- Negligible effect
Correct answer: Large effect
Cohen's d of 0.85 exceeds 0.80, which is the conventional threshold for a large effect size.
Question 2: A stacked bar chart is used to display data. What advantage does it have over a simple bar chart?
- It shows how individual parts contribute to a whole within each category (Correct answer)
- It can display more categories on the x-axis
- It removes the need for a legend
- It is easier to read exact values from
Correct answer: It shows how individual parts contribute to a whole within each category
Stacked bar charts show both the total value and the composition of each bar, revealing part-to-whole relationships within categories.
Question 3: Which measure of central tendency is most affected by extreme outliers?
- Mode
- Median
- Mean (Correct answer)
- Range
Correct answer: Mean
The mean is calculated using all values, so extreme outliers can significantly pull it higher or lower, unlike the median which is based on rank position.
Question 4: A longitudinal study tracks the same participants over 10 years. What type of data does this design produce?
- Cross-sectional data
- Retrospective data only
- Repeated measures data over time (Correct answer)
- One-time experimental data
Correct answer: Repeated measures data over time
Longitudinal studies collect data from the same individuals at multiple time points, producing repeated measures that allow tracking of change over time.
Question 5: In a frequency table, the 'cumulative frequency' column is increasing. What does each entry in this column represent?
- The frequency of only the current interval
- The total frequency from the first interval up to and including the current one (Correct answer)
- The percentage of the total for each interval
- The difference between consecutive frequencies
Correct answer: The total frequency from the first interval up to and including the current one
Cumulative frequency is a running total that adds each interval's frequency to all previous intervals, showing how many values fall at or below each point.
Question 6: A graph's legend labels one line as 'control group' and another as 'experimental group.' Why is this distinction important for interpretation?
- It indicates which group had more participants
- It allows the reader to compare outcomes between the untreated baseline and the treated condition (Correct answer)
- It shows which group performed better on all measures
- It identifies which group's data is more reliable
Correct answer: It allows the reader to compare outcomes between the untreated baseline and the treated condition
The control group provides the baseline against which the experimental group's results are measured, making the legend essential for interpreting any observed differences.
Question 7: A researcher reports that R² = 0.72 for a regression model. What does this value indicate?
- 72% of the variance in the outcome variable is explained by the predictor(s) (Correct answer)
- There is a 72% probability the findings are correct
- The correlation coefficient is 0.72
- 72% of participants showed the predicted outcome
Correct answer: 72% of the variance in the outcome variable is explained by the predictor(s)
R² (the coefficient of determination) represents the proportion of variance in the dependent variable that is explained by the independent variable(s) in the model.
EAP Interpreting Academic Data 4
A research article states that the effect size (Cohen's d) is 0.85.
How is this generally interpreted?