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Difficulty: MediumStatistical Inference and Hypothesis Testing

A clinical research committee is reviewing several proposed study protocols. For each proposed study design, select the most appropriate statistical method for primary data analysis.

  • Comparing mean hemoglobin levels across four distinct, independent ethnic groups to identify baseline population differences.Analysis of variance (ANOVA)
  • Assessing the relationship between the presence of a specific genetic mutation (positive/negative) and the occurrence of deep vein thrombosis (yes/no).Chi-square test
  • Analyzing differences in resting heart rate within a single cohort of athletes, measured immediately before and 24 hours after a competitive event.Paired t-test
  • Evaluating the degree of linear association between maternal age (in years) and offspring birth weight (in grams).Pearson correlation coefficient

Answer

The scenarios match with ANOVA, Chi-square test, Paired t-test, and Pearson correlation coefficient respectively.
Selecting a statistical test requires accurately identifying the independent and dependent variables and their data types. Continuous data compared across three or more independent groups requires ANOVA. Categorical outcomes compared against categorical exposures utilize the Chi-square test. Continuous data measured twice in the same subjects necessitates a paired t-test to account for dependent sampling. Evaluating the linear relationship between two continuous variables is accomplished using the Pearson correlation coefficient.

Step-by-Step Solution

1
Identify the variable types for the first scenario.
The outcome is continuous (hemoglobin) and the independent variable is categorical with four groups (ethnicity).
Determining whether data is continuous or categorical and the number of groups dictates the choice of statistical test.
2
Identify the variable types for the second scenario.
Both the independent (mutation status) and dependent (DVT occurrence) variables are categorical.
Comparing proportions between categorical variables requires a specific statistical test.
3
Identify the variable types and sample dependency for the third scenario.
The outcome is continuous (heart rate) and the samples are dependent (same athletes measured twice).
Dependent versus independent continuous data require different forms of t-tests.
4
Identify the variable types and research objective for the fourth scenario.
Both variables are continuous (maternal age, birth weight), and the objective is to evaluate their linear association.
Testing the linear association between two continuous variables requires correlation analysis.

Key Concept

Selection of the appropriate statistical test depends on the type of data (continuous vs. categorical) and the study design (independent groups vs. paired measurements).
Estimated Time:1m 30s
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Topics

Statistical Inference and Hypothesis Testing

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