Chi-square test

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Name of Epidemiologist

NEET PG High-Yield: Chi-Square Test (\chi^2)

The Chi-square test is a non-parametric test used to determine if there is a significant association between two categorical variables.

Key Characteristics

Parameter Detail
Data Type Categorical (Nominal or Ordinal).
Purpose To compare observed frequencies with expected frequencies.
Degree of Freedom (r - 1) \times (c - 1), where r = rows and c = columns.
High-Yield NEET PG Pearls:

  • Assumptions: Total sample size should be > 50; expected frequency in any cell should not be < 5.
  • Yates’ Correction: Applied for continuity when the table is a 2 \times 2 and the sample size is small.
  • Fisher’s Exact Test: Used instead of Chi-square if expected frequencies are < 5 in a 2 \times 2 table.
  • Clinical Use: Often used in studies to compare the proportion of subjects with a disease between two exposure groups.