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Difficulty: MediumInferential Statistical Tests

Match each clinical study design and variable configuration with the most appropriate inferential statistical test used for data analysis.

  • Comparing mean serum cholesterol levels (a normally distributed continuous variable) among three independent patient cohorts receiving different statin therapies.One-way Analysis of Variance (ANOVA)
  • Comparing the incidence of postoperative wound infections (a nominal categorical variable) between patients receiving prophylactic antibiotics versus placebo.Chi-square test
  • Comparing median urinary protein excretion (a highly skewed continuous variable) between patients with diabetic nephropathy and healthy controls.Mann-Whitney U test
  • Evaluating changes in mean tumor volume (a normally distributed continuous variable) within the same group of oncology patients before and after a targeted 12-week chemotherapy regimen.Paired t-test

Answer

The correct matches align three cohorts to ANOVA, categorical infection incidence to the Chi-square test, skewed protein levels to the Mann-Whitney U test, and paired before-and-after tumor volumes to the Paired t-test.
Each study design correctly matches with the statistical test that accommodates its specific combination of variables, group numbers, and data distribution.

Step-by-Step Solution

1
Analyze the first scenario involving three independent cohorts and a continuous, normally distributed variable.
Identified as requiring a parametric test for >2 independent groups, which is ANOVA.
ANOVA compares means across three or more independent groups when data is normally distributed.
2
Analyze the second scenario involving the incidence of infection (categorical data) in two independent groups.
Identified as requiring a test for categorical data proportions, which is the Chi-square test.
The Chi-square test evaluates associations and compares frequencies between categorical variables.
3
Analyze the third scenario involving two independent groups and a highly skewed continuous variable.
Identified as requiring a non-parametric test for two independent groups, which is the Mann-Whitney U test.
Non-parametric tests are required when continuous data heavily violates the assumption of a normal distribution.
4
Analyze the fourth scenario involving continuous, normally distributed data measured twice in the same cohort.
Identified as requiring a parametric test for paired or matched data, which is the Paired t-test.
The paired t-test compares means between two related measurements taken from the same individual.

Key Concept

Selection of the appropriate inferential statistical test is determined by the number of comparison groups, the independence of those groups (paired vs. unpaired), the data type (continuous vs. categorical), and the underlying distribution (normal vs. skewed).
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Inferential Statistical Tests

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