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Difficulty: EasyInferential Statistical Tests

An occupational health physician at a large manufacturing plant is investigating the physiological impact of working non-traditional hours. To do this, the physician measures early morning serum cortisol levels, which follow a normal distribution, in 45 employees who exclusively work the day shift and 45 different employees who exclusively work the night shift. The goal is to determine if there is a significant difference in the mean cortisol levels between these two groups. Which of the following is the most appropriate statistical test to analyze the data in this study?

  1. A
    Analysis of variance
  2. B
    Chi-square test
  3. C
    Paired t-test
  4. D
    Pearson correlation coefficient
  5. Two-sample t-testAnswer

Answer

Two-sample t-test
The two-sample (independent) t-test is the most appropriate statistical method to compare the means of a continuous, normally distributed dependent variable (serum cortisol levels) between two independent categorical groups (day shift workers and night shift workers).

Step-by-Step Solution

1
Identify the dependent (outcome) variable and its data type.
The dependent variable is serum cortisol level, which is a continuous and normally distributed variable.
The type of the dependent variable determines the main branch of statistical tests (e.g., parametric tests for normal continuous data).
2
Identify the independent (predictor) variable and its data type.
The independent variable is the shift type (day shift vs. night shift), which is a categorical variable consisting of two independent groups.
The number of groups and their relationship (independent vs. matched) narrows down the specific statistical test.
3
Select the appropriate test based on the variable characteristics.
Comparing a normal continuous variable between two independent categorical groups requires a two-sample (independent) t-test.
This test is specifically designed to determine if there is a statistically significant difference between the means of two unrelated groups.

Key Concept

Statistical Test Selection for Two Independent Groups
Estimated Time:45s
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Topics

Inferential Statistical Tests

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