Create a new categorical variable $($age$\_4$cat$)$ from RIDAGEYR using code in this form:

DataFrame$Variable$[$Condition$]<-$ NewValue

Create the following categories of age: $25-34,35-44,45-54,55-65$

Use the expss package to add value labels to the new variable.

Use the as$.$factor function to convert the new variable to a factor variable.

Use the by and summary commands to calculate descriptive statistics for INDFMPIR separately for each age group. Software is Rstudio. I am not sure how to do this.