APA Style T-Test Reporting Guide
A Step-by-Step Guide
The t-test is a statistical procedure used to determine whether there is a significant difference between the means of two groups.
When writing the results of a t-test in APA style, it is essential to report the relevant statistical information clearly and concisely.
Here is a step-by-step guide on how to do so:
STEP-BY-STEP
1. Start by stating the purpose of the t-test. This should include a brief description of the research question or hypothesis being tested.
2. Report the sample size for each group. It is essential to specify whether the samples are independent or paired.
3. Report the mean and standard deviation for each group. These values provide information about the data distribution and allow readers to gauge the spread of the scores.
4. Report the t-statistic and associated degrees of freedom (df). The t-statistic is a measure of the difference between the means of the two groups, and the degrees of freedom represent the number of scores that are free to vary within the sample.
5. Report the p-value. The p-value measures the probability that the observed difference between the means could have occurred by chance. A p-value of less than 0.05 is generally considered statistically significant, meaning that the observed difference is unlikely to have occurred by chance.
6. Report the effect size. In addition to the statistical significance, it’s crucial to report the effect size, which measures the magnitude of the difference between the means of the two groups. Effect size provides context for the practical significance of the results. The commonly used effect size measure for t-tests is Cohen’s d. Make sure to include the effect size value in your results section and an interpretation based on established guidelines (e.g., small, medium, or large effect).
7. Interpret the results. Based on the t-statistic, degrees of freedom, and p-value, you can determine whether the observed difference between the means of the two groups is statistically significant. If the p-value is less than 0.05, you can conclude that there is a statistically significant difference between the means of the two groups. If the p-value is greater than 0.05, you can conclude that there is no statistically significant difference between the means of the two groups.
8. Report any additional relevant information. If you conducted other relevant findings or statistical tests, be sure to include this information in your results section.
EXAMPLE
Here is an example of how to report the results of a t-test in APA style:
“The purpose of this study was to examine the effect of a new study strategy on test performance. A total of 50 students were randomly assigned to either the experimental group (n = 25) or the control group (n = 25). The experimental group received training on the new study strategy, while the control group received no intervention.
The mean test score for the experimental group was 85, with a standard deviation of 10. The mean test score for the control group was 80, with a standard deviation of 15. A paired-samples t-test was conducted to compare the means of the two groups. The t-statistic was 2.17, with df=49 (p < .05).
The effect size for the difference between the groups was calculated using Cohen’s d, resulting in a value of 0.39, which is considered a small to medium effect.
The results of this study indicate that there is a statistically significant difference between the mean test scores of the experimental group and the control group. Specifically, the experimental group had a higher mean test score than the control group. These findings suggest that the new study strategy effectively improved test performance, with a small to medium effect size.“
HOW TO REPORT COHEN'S D IN APA STYLE?
In addition to reporting the statistical significance of the results of a t-test, it is also essential to report the effect size.
The effect size measures the strength of the relationship between the two variables being tested.
It provides a way to quantify the difference between the means of the two groups. It can help readers better understand the practical significance of the results.
Cohen’s d is a standardized measure of effect size, representing the difference between the means of the two groups in terms of standard deviations.
To calculate Cohen’s d, you will need to know each group’s mean and standard deviation.
Here is the formula for Cohen’s d:
d = (mean1 – mean2) / pooled standard deviation
Once you have calculated Cohen’s d, you can use the following guidelines to interpret the results:
| Cohen's d | Effect size |
|---|---|
|
0.00-0.19 |
Very small |
|
0.20-0.49 |
Small |
|
0.50-0.79 |
Medium |
|
0.80+ |
Large |
Note: These thresholds are merely guidelines and may vary depending on the research context.
To report the effect size in your APA style t-test results, you can include Cohen’s d value in the results section of your paper. For example:
“The results of this study indicate that there is a statistically significant difference between the mean test scores of the experimental group and the control group. Specifically, the experimental group had a higher mean test score than the control group (M = 85, SD = 10) than the control group (M = 80, SD = 15). A paired-samples t-test revealed a t-statistic of 2.17, with df=49 (p < .05). The effect size was medium, with a Cohen’s d of 0.53.“
By reporting the effect size and the statistical significance of the results, you can give readers a complete understanding of the relationship between the two tested variables.
CONCLUSION
In conclusion, reporting the results of a t-test in APA style is a critical aspect of conducting and communicating research.
Following the guidelines outlined here, you can effectively report the relevant statistical information clearly and concisely.
This includes stating the purpose of the t-test, reporting the sample size and descriptive statistics for each group, reporting the t-statistic and associated p-value, interpreting the results, and reporting any additional relevant information.
Additionally, it is important to report the effect size, as this measures the strength of the relationship between the two variables being tested.
By including all of these elements in your results section, you can provide readers with a complete and thorough understanding of your findings.
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