Use formula in place of row number?

I need to come up with a way to determine the appropriate range for a countif function. The column is known and unchanging, the row number depends on how many items there were in the previous category.

For example: I would need to count a variable in column C from rows 3-5 shown below, because they are all in the same category (2). Number of rows in each category varies greatly. Tried using nested if functions but that doesn't scale.

1 1
2 1
3 2
4 2
5 2
6 3

ideally, would use something like =countif(C"match(...):C"match(...),1) but can't figure out how to or if I can use the match function in place of the row number.

Appreciate your thoughts.

I should have clarified...the book has 2 sheets. im analysing news coverage for the appearance of certain terms. in one sheet, each row is a particular instance of a term, with a number of columns for different classifications. in another sheet, i need to have totals for each classification by article. trouble is, each article has a different number of terms.

ie

1 article 1 term 1
2 article 1 term 2
3 article 1 term 3
4 article 2 term 1
5 article 3 term 2
6 article 3 term 2

I need to count how many times term 1 appears in each article, etc. The term sheet will be pretty extensive so I'd rather not do it by hand for each article

Good call. Heres an example of what i'd like to be able to do. The term sheet contains entries for every occurrence of particular terms. Article sheet counts the terms by articles. There are a number of other data points for each entry in the term sheet but the mechanics are the same. There will ultimately be hundreds of entries in the term sheet and probably about 50 articles. Problem with the countif( function is caused by the variable ranges for each article (since the number of relevant terms in each article varies significantly). Open to any suggestions. Thanks in advance.