To identify influential outliers (Cook’s Distance).
To verify constant variance across the range of data.
Using poly() to fit non-linear shapes within a linear framework. Linear Models with R
To check for non-linearity and heteroscedasticity. Normal Q-Q: To ensure residuals are normally distributed.
At the heart of linear modeling in R is the lm() function. Its syntax— response ~ predictor —perfectly mirrors the statistical notation of To identify influential outliers (Cook’s Distance)
Using * or : to see if the effect of one variable depends on another.
Linear models form the backbone of modern statistical analysis, providing a transparent and mathematically rigorous way to understand relationships between variables. In the R programming environment, these models are not just a collection of formulas but a comprehensive ecosystem for data exploration, diagnostic testing, and prediction. The Foundation: The lm() Function To check for non-linearity and heteroscedasticity
Wrapping variables in log() or sqrt() directly within the model call. Beyond the Fit: Diagnostics and Validation