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Difficulty: MediumInferential Statistical Tests

Clinical investigators are conducting a prospective, randomized study to evaluate the efficacy of a novel telemedicine-based health coaching intervention compared to standard care in adults with metabolic dysfunction-associated steatotic liver disease (MASLD). A total of 300 patients are randomly assigned in a 1:1 ratio to the two independent study arms.

At the 12-month follow-up, the research team plans to analyze three distinct outcomes:
1. Mean absolute change in body mass index (BMI) from baseline, which preliminary data show is continuous and normally distributed.
2. Rate of progression to severe hepatic fibrosis, categorized as a binary outcome (progression occurred: yes or no).
3. Patient-reported quality of life score, measured on a continuous scale from 0 to 100, which exhibits a heavily skewed, non-normal distribution.

Which of the following statistical approaches are appropriately selected for analyzing these outcomes? (Select all that apply)

  1. Independent samples t-test to compare the mean absolute change in BMI between the telemedicine and standard care groupsAnswer
  2. B
    Paired t-test to compare the mean absolute change in BMI between the telemedicine and standard care groups
  3. Chi-square test to compare the rate of progression to severe hepatic fibrosis between the telemedicine and standard care groupsAnswer
  4. D
    Analysis of variance (ANOVA) to compare the rate of progression to severe hepatic fibrosis between the telemedicine and standard care groups
  5. E
    Wilcoxon signed-rank test to compare the patient-reported quality of life scores between the telemedicine and standard care groups

Answer

The appropriate tests are the independent samples t-test for comparing the normally distributed continuous BMI changes and the Chi-square test for comparing the categorical fibrosis progression rates between the two independent groups.
The independent samples t-test correctly evaluates the difference in means of a continuous, normally distributed variable between two distinct patient groups. Furthermore, the Chi-square test is the optimal standard method for comparing proportions of a categorical outcome (such as a yes/no disease progression state) between two independent cohorts.

Step-by-Step Solution

1
Determine the relationship between the study groups.
The telemedicine and standard care groups are randomized and independent of each other.
Identifying whether groups are independent or paired dictates the entire category of statistical tests available.
2
Analyze the data type and distribution for the BMI outcome.
The BMI outcome is continuous and normally distributed.
Continuous, normally distributed data compared across two independent groups requires an independent samples t-test.
3
Analyze the data type for the fibrosis progression outcome.
The fibrosis progression outcome is a binary categorical variable (yes/no).
Categorical outcomes compared between independent groups are analyzed using a Chi-square test (or Fisher's exact test if sample sizes are very small).
4
Analyze the data type for the quality of life outcome.
The quality of life score is continuous but has a heavily skewed, non-normal distribution.
Non-normally distributed continuous data compared across two independent groups requires a non-parametric test, specifically the Mann-Whitney U test (also known as the Wilcoxon rank-sum test).
5
Evaluate the available options against the optimal test selections.
Only the independent samples t-test for BMI and the Chi-square test for fibrosis progression correctly match the data types and study design.
Matching the derived test requirements to the options eliminates incorrect tests like ANOVA for categorical data and paired tests for independent samples.

Key Concept

Selection of statistical tests based on data type (continuous vs. categorical), data distribution (normal vs. skewed), and sample independence (independent vs. paired).
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Inferential Statistical Tests

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