Why does my textbook say this is not a frequency distribution / not categorical data? It looks like one to me I am reading an intro to statistics textbook, and they were telling us about pie charts.
They were saying that pie charts can be used for categorical data sets. But then they said
that they can be used for "other purposes" as well (without specifying what is different about those other purposes). Instead they gave an example that I have screenshot-ed below. In the example they show a table with types of grapes that were grown in california. The textbook says this table is not a frequency distribution. But from what the textbook said before, it seems like a frequency distribution to me (Here is how they define frequency distribution: "Frequency distribution for categorical data: A table that displays frequencies, and sometimes relative frequencies, for each of the possible values of a categorical variable."). What is the difference here?
Is the difference simply that these numbers are not from a sample but are estimates of the entire population? I can't see what else it would be, because correct me if I'm wrong but grapes would be the population here and type of grape would be the categories right? (the textbook emphasized that the target population could be anything not just people) So this would be a categorical data set. So why isn't the table a frequency distribution?


To consider this a frequency chart, we'd have to consider each ton of grape production to be the variable of interest, and we would count up the tons in each category.  However, "how many times did a ton of grapes get turned into white wine in 2015" is not the way we typically think about it.  We aren't interested in counting the number of (logical) events during which a ton of grapes got turned into each wine type, we are interested in summing up the tons of grapes to get a total.  A total is not a frequency, a frequency is a count.
