Statistical Method for Comparing Blood Pressures Between Two Groups
The Student t-test (option C) is the appropriate statistical method for comparing blood pressures between two groups. 1, 2
Why Student t-test is Correct
The Student t-test is specifically designed for comparing means of continuous numerical variables (such as blood pressure measurements) between two independent groups. Blood pressure is a continuous variable that is typically normally distributed in populations, making the t-test the most appropriate choice.
When to Use Student t-test for Blood Pressure Comparisons:
- When comparing mean systolic or diastolic blood pressure between two treatment groups
- When data follows a normal distribution (or sample size is large enough)
- When comparing independent samples (e.g., treatment vs. control)
Why Other Options Are Not Appropriate
Chi-square test (option A):
- Used for categorical variables, not continuous measurements like blood pressure
- Appropriate for comparing proportions or frequencies, not means 1
- Example: Would be used to compare the proportion of hypertensive patients between groups, not the actual BP values
Correlation Coefficient (option B):
- Measures the strength and direction of association between two continuous variables
- Does not test for differences between groups
- Would be used to assess relationship between BP and another continuous variable (e.g., BMI)
Mann-Whitney U test (option D):
- Non-parametric alternative to t-test when data is not normally distributed
- Less powerful than t-test when normality assumptions are met
- Would be appropriate only if blood pressure measurements were severely skewed 2
Important Considerations When Using t-test for Blood Pressure
- Check normality: Blood pressure should be normally distributed within each group
- Variance equality: Test assumes equal variances between groups; if variances differ significantly, use Welch's t-test (modified t-test) 3, 4
- Sample size: Larger sample sizes increase reliability of results
- Multiple measurements: When multiple BP measurements are taken from the same subject, paired t-test or repeated measures ANOVA may be more appropriate 5
In clinical research, the t-test is routinely used to compare blood pressure differences between intervention and control groups, as evidenced by its application in numerous hypertension studies 6.