knitr: :opts_chunk$set (fig . width=8, fig . height=6) #set size of graphs # install . packages ("gmodels") #execute this if you have not yet installed gmodels library (gmodels) Data 1 Description: Falls are of major concern among polio survivors. Researchers wanted to determine if the frequency of falls of 231 polio survivors was associated with wheelchair use. Subjects were cross-classified according Wheelchair Use (Yes/No) and Fallers (Yes/No). polio. tab 18mos') ) ACUTEf