It's the which

Working on a post for the economics blog, as usual. Here is my opening paragraph:

GDP is a measure of final spending only. Not all spending. For example, GDP excludes things that can be taken as corporate tax deductions. Things like the "cost of goods sold" which, if you buy stuff in order to sell it, is clearly not "final" spending when you buy it.

This stuff is clear to me because I know it. But when I read the paragraph it isn't clear to me. The trouble is that last sentence. It doesn't make things clear. It makes things complicated:

Things like the "cost of goods sold" which, if you buy stuff in order to sell it, is clearly not "final" spending when you buy it.

I already put the word "clearly" in there, but it doesn't make the sentence clear. The sentence is constructed as one thought stuffed inside another, before the first is fully stated. So the reader has to capture the first half of the first idea and hold on to it, but set it aside in order to capture the second idea, and then capture the second half of the first idea, and then retrieve the first half of that idea and combine the two halves, and then hope to make sense of the assembled thought. This is far too much to expect of the reader. I can't do it myself, and I'm the one who wrote it.

The problem arises with the "which", which interrupts the first thought in order to present the second. I think I have to get rid of the "which". I think I have to break the sentence in two. God forbid -- gasp! -- an extra sentence???

I can do that:

The "cost of goods sold" is not "final" spending...

Nope. That's a conclusion. I have to prove it first.

Things like the "cost of goods sold". If you buy stuff in order to sell it, it is clearly not "final" spending when you buy it.

That helps. End the sentence instead of using "which". Huh, and now that I've made it clear I can get rid of the "clearly":

Things like the "cost of goods sold". If you buy stuff in order to sell it, it isn't "final" spending when you buy it.

Much better! Almost there, I think. But I don't want to say it isn't "final" spending. I want to say it's not final spending:

Things like the "cost of goods sold". If you buy stuff in order to sell it, it's not "final" spending when you buy it.

I think it's good. I have to try the whole paragraph now:

GDP is a measure of final spending only. Not all spending. For example, GDP excludes things that can be taken as corporate tax deductions. Things like the "cost of goods sold". If you buy stuff in order to sell it, it's not "final" spending when you buy it.

No, I have to change the tense... Oh, but that messes up the "it's not". Maybe like this:

GDP is a measure of final spending only. Not all spending. For example, GDP excludes things that can be taken as corporate tax deductions. Things like the "cost of goods sold". If you bought stuff in order to sell it, 'twas not "final" spending when you bought it.

Nope, not like that.

I have to wrap it up. Fit it into the essay, fix that contraction, summarize the thought, and move on to the next paragraph.

So it goes.