Summary
In this chapter, we learned how to plot variables to see whether they have a link before conducting statistical analysis. After this, we reviewed the differences between the expected values and the results from the linear model. These differences are the input for the formulas of the coefficient of determination and correlation, which show the variables' level of relationship and whether they are direct or inversely proportional.
Statistical methods such as t-statistics and the p-value tell us whether we can reject the null
hypothesis. If the slope is zero, there is no relationship between the variables.
Once we have a level of confidence regarding the relationship between variables, we can conclude that the linear regression model is useful for building predictions. In the next chapter, we will write the formula of a simple (single-variable) regression model.