Factors are qualitative data that are associated with categorization or the description of an attribute. Factors are often (but not always) represented with wo

Question

Factors are qualitative data that are associated with categorization or the description of an attribute. Factors are often (but not always) represented with words, like colors or names of things. On the other hand, numeric data are generated by numeric measurements. R can store values as factors or numbers, but sometimes you have a choice of how to represent values.

1) I have two apples, one banana, one cherry. Does it make sense to calculate the "average" of these things? Would you code that as a factor or a numeric value in R?

2) I have four quiz scores: 94, 93, 85, and 0. What is the mean (average) of my quiz scores? Would you code this as a factor or a numeric value in R?

3) In another class, I received these grades on my quizzes: two As, one B, and one F. What is the mean (average) of my grades? Would you code that as a factor or a numeric value in R?

4) How would you explain the difference in mean values obtained in #2 and #3 above?

Answer 1

Item 1: No average is possible here, because the colors are not numbers, and are therefore not subject to numerical analysis. The colors would be coded as "factors"
 
Item 2: The average here equals the sum of the four scores (94+93+85+0=272) divided by 4, which equals 68. The result would be coded as a number.
 
Item 3: No average is possible here, because the letter grades are not numbers. The letter grades would be coded as "factors"
 
Item 4: There is no difference to explain. The word difference means the result of subtraction between two numbers, which is not the case here. If the letter grades were converted to numbers, then an average could be computed.