Normal distribution metrics: Evaluating model assumptions in JC math

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Frequently Asked Questions

Checking for normality allows us to validate the use of statistical tests that assume a normal distribution, ensuring the reliability and accuracy of our models conclusions.
Use histograms, normal probability plots (Q-Q plots), or box plots to visually inspect the data. A bell-shaped histogram and data points closely aligned to a straight line on a Q-Q plot suggest normality.
The Shapiro-Wilk test, Kolmogorov-Smirnov test, and Anderson-Darling test are commonly used to statistically test the null hypothesis that the data is normally distributed.
A p-value above a chosen significance level (e.g., 0.05) suggests that we fail to reject the null hypothesis, providing evidence that the data may be normally distributed. A p-value below the significance level suggests the data is likely not normally distributed.
Violating normality can lead to inaccurate p-values and confidence intervals, potentially leading to incorrect conclusions about the data and affecting the validity of the model.
Consider transformations (e.g., logarithmic, square root) to make the data more normal, use non-parametric tests that dont assume normality, or consider alternative modeling approaches.
With small sample sizes, it can be difficult to definitively determine normality, and tests may lack power. Larger sample sizes provide more reliable assessments of normality.