You’re taking the notion of “reading level” more seriously than the people who made up this method. Here’s the sort of discussion that probably went on in creating the method.
Person 1: I need a simple method by which someone can determine the reading level of a written passage. You know, one which will tell us which grade level the passage is appropriate for.
Person 2: Hmm, that’s not going to be easy. At the moment, we do this by having an expert on reading education read the passage. They have a pretty good intuitive knowledge of how difficult a passage is to read and thus what grade level it’s appropriate for.
Person 1: That’s too complicated. I need a way to do this so that anyone with a high school degree can do this with no more than a couple of minutes of looking at the passage.
Person 2: Well, what the experts are doing is looking at the words and the grammar used in the passage. Let’s see, we can create a dictionary of all English words with their reading level and an annotated grammar that would allow us to mark the passage for its . . .
Person 1: No, no, no! That’s too difficult. I don’t want some huge program that only a computer could do. I want a simple system that would allow a person to determine the reading level. It can’t be something complex that would take a long time to learn. The person should be able to learn the system in fifteen minutes.
Person 2: Hmm, well, I suppose you could just use the number of polysyllabic words in the passage.
Person 1: What’s a polysyllabic word? One with more than one syllable?
Person 2: No, it would probably be better to use three or more syllables as the cut-off. I’d have to ask a statistician to figure out the correlation between the number of words and the grade level.
Person 1: Well, do so.
Person 2: Statistician, can you create a formula that relates the number of polysyllabic words and the reading level.
Person 3: Sure. Take a bunch of medium-sized reading passages. Have your experts go through them and use their intuitions to mark their reading levels. Give me the results.
Person 2: O.K., here you go.
Person 3: Well, I looked at them, and it appears that the best thing to do is to count the number of polysyllabic words in any 30 sentences. Call this number n. The reading level is 9.876n + n3.841 + ln(n) + . . .
Person 1: No, no, no, that’s too complicated. You’ve got to simplify it.
Person 3: Well, I can’t use a linear formula. That doesn’t fit the curve at all. I suppose I could just use a second-degree equation. Are you assuming that these people can square a number?
Person 1: O.K., but it’s got to be squaring a whole number and adding a whole number. It’s too complicate to use decimals or fractions.
Person 3: Well, O.K., here’s a formula using just squaring and adding whole numbers. It’s really not very accurate.
Person 1: Who cares about accurate? I just need a method that any bonehead can use. Nobody’s going to question the answers that the formula gives. These people think that any number that comes out of a mathematical formula is obviously accurate. Remember, these are people gullible enough to think that IQ scores are tremendously precise.