Understanding the assumptions of Fisher's Exact Test.

📚 Quick Study Guide

• 📏 Independence: The observations in your contingency table must be independent of each other. This means one data point doesn't influence another.
• 🧮 Fixed Margins: Fisher's Exact Test conditions on the row and column totals being fixed. In other words, the marginal totals are considered given.
• 🎲 Random Sampling: The data should come from a random sample. This helps ensure the sample is representative of the population.
• 📊 Categorical Data: Fisher's Exact Test is designed for categorical data arranged in a contingency table (usually 2x2).
• 🚫 No Small Expected Counts Rule: Unlike Chi-Square, Fisher's Exact Test is reliable even with small sample sizes where expected counts are low. This is a key advantage!

Practice Quiz

1. Which of the following is a key assumption of Fisher's Exact Test?
   1. Independence of observations
   2. Large sample size
   3. Normally distributed data
   4. Equal variances
2. What does it mean for the margins to be 'fixed' in Fisher's Exact Test?
   1. The row and column totals are allowed to vary randomly.
   2. The row and column totals are considered given or fixed.
   3. Only the row totals are fixed.
   4. Only the column totals are fixed.
3. Fisher's Exact Test is MOST appropriate for which type of data?
   1. Continuous data
   2. Ordinal data
   3. Categorical data
   4. Interval data
4. Why is Fisher's Exact Test often preferred over the Chi-Square test when dealing with small samples?
   1. It is computationally simpler.
   2. It doesn't require the assumption of fixed margins.
   3. It is more accurate when expected cell counts are small.
   4. It always yields a lower p-value.
5. Which of the following scenarios violates the independence assumption of Fisher's Exact Test?
   1. Analyzing survey responses from randomly selected individuals.
   2. Examining the relationship between gender and political affiliation.
   3. Studying paired data where each observation influences the other.
   4. Comparing the effectiveness of two different drugs in separate trials.
6. What is the consequence of violating the assumption of fixed margins in Fisher's Exact Test?
   1. The test will still be valid, but the p-value will be slightly different.
   2. The test results may be unreliable.
   3. The test cannot be performed.
   4. The test will automatically correct for the violation.
7. Which statement BEST describes the application of Fisher's Exact Test?
   1. Testing for differences in means between two groups.
   2. Analyzing the correlation between two continuous variables.
   3. Examining the association between two categorical variables in a small sample.
   4. Predicting future values based on past trends.