Discussion Topics and Questions
Find a published research study on a topic that you could use for your DNP project that used an independent t-test and find this information from the study:
- Give the purpose/objective/aim of the study exactly as it is written in the study.
- What is the population in the study?
- What is the independent (treatment or intervention) variable?
- What is the dependent (outcome) variable? If there are multiple dependent variables, choose only one for the focus of this discussion. What is its
- level of measurement (nominal, ordinal, interval, ratio)? Is it a categorical or continuous variable? You can often determine this as you read the Methods section of the report.
- If a hypothesis was stated in the article for the independent t-test, give it here and label it as a Ho or Ha. Write the stated hypothesis as an equation. Write the other hypothesis (the Ho or Ha that was not given) in words and an equation. If a hypothesis was not stated, then restate the purpose/objective/aim as a null hypothesis in words and equation format. Do this for both a null and alternative hypothesis. Again, focus on only one independent variable and one dependent variable. Use the format on pp. 217-218 of Kim et al. (2022) and the handout attached to the announcement for this week.
- What are the assumptions for the independent t-test (Kim et al., 2022, p. 217)? Are they met in this study? Provide information given in the study that can be used to determine whether each assumption is or is not met. What information is not given?
- What alpha level (level of significance) was used?
- What are the groups that were tested?
- Give the mean values with the standard deviation for the outcome variable for the groups.
- Give the t-statistic, if provided, and p-value for the difference in mean values for the DV you are focusing on.
- Specifically state the p-value rule for the results of this study to determine whether to reject or fail to reject the null hypothesis.
- Based on the decision made about the null hypothesis, what type of error is possible (Kim et al., 2022, pp. 131-132 and Table 7-3).
- What are the usual causes of this type of error? Are any of them present in the methodology for this study?
- Give the confidence interval for the difference in mean values, if provided. Use the confidence interval around a difference in mean values rule (given in the Overview in Module 5) to determine whether to reject or fail to reject the null hypothesis.
- The effect size for t-test results is reported as a Cohen’s d statistic (Kim et al., (2022, p. 134). Give this value, if given in the study, and interpret what it means (use the guidelines in the Overview in Module5) in terms of the magnitude or clinical meaningfulness (clinical significance) of the result. If not given, determine the clinical significance of the difference in mean values by using your knowledge, critical thinking, and experience with your patients and setting, would you incorporate the intervention or treatment into your practice? Is your evaluation of the clinical significance of the findings consistent with the statistical significance for the findings and the value of the effect size? Explain your rationale.
Find a published research article the used a paired t-test to test the difference in mean values at two different times.
- State the null and alternative hypotheses in words and an equation for the outcome variable. You will need to write this from the purpose/objective/aim if a hypothesis is not given.
- Describe the two times the dependent (outcome) variable was measured.
- Give the two mean values for the outcome variable for the two times.
- Give the t-statistic and p-value for the difference in mean values.
- Specifically state the p-value rule to determine whether to reject or fail to reject the null hypothesis.
