Can you do regression with nominal variables?

Nominal logistic regression, also known as multinomial logistic regression, models the relationship between a set of independent variables and a nominal dependent variable. A nominal variable has at least three groups which do not have a natural order, such as scratch, dent, and tear.

What type of regression should be conducted when the dependent variable has more than two classes?

Logistic regression
If the nominal dependent variable has two categories Logistic regression should be conducted. If it has more than two categories Multinomial Regression should be done.

What statistical test would be used with interval or ratio data with multiple dependent variables?

A correlation is useful when you want to see the relationship between two (or more) normally distributed interval variables.

Which regression model is best?

A low predicted R-squared is a good way to check for this problem. P-values, predicted and adjusted R-squared, and Mallows’ Cp can suggest different models. Stepwise regression and best subsets regression are great tools and can get you close to the correct model.

Which is the best regression model?

The best model was deemed to be the ‘linear’ model, because it has the highest AIC, and a fairly low R² adjusted (in fact, it is within 1\% of that of model ‘poly31’ which has the highest R² adjusted).

What statistical test is used for ratios?

A ratio variable can be used as a dependent variable for most parametric statistical tests such as t-tests, F-tests, correlation, and regression.

Can multiple regression have categorical variables?

In linear regression the independent variables can be categorical and/or continuous. But, when you fit the model if you have more than two category in the categorical independent variable make sure you are creating dummy variables.