Very interesting. I was extremely accurate, but the 50th percentile point helped tremendously.

I started drawing from the left, with the approach given below, however by the time I was at the 50th percecntile mark I was nowhere near 50% so I moved those up a bit. Around 40th to 60th percentile is when I would have done the worst without the aid of the middle point. (Which brought my graph up.)

My graph: http://imgur.com/a/hjvdf

- You drew a more accurate picture of reality than about 98 percent of people who have tried so far.

- Your line was relatively straight, reflecting one of the more striking findings of this research: The relationship between college enrollment and parental-income rank is linear.

- Your guess was extremely accurate. Is that you, Raj Chetty?

This was my methodology for drawing "extremely accurately":

Starting at left (where I started drawing) I reasoned, primary and secondary education is free and mandatory in the united states, and there are huge scholarship and other support programs. So while the poorest of the poor have everything going against them in terms of family support and even culturally, plus likely the pressure of starting to work early, still, I reasoned at least one out of five can make use of the opportunities and begin attending college.

I then intended to proceed up steadily, but I intended to level off somewhat between the 40th and 70th percentile, because a lot of average-income people simply start working. As you can see, the free point moved my graph up (via adjustment by me when I saw that I was still short of it at that point) heavily.

I had then intended to proceed up linearly to a very high rate of college attendance, and after a certain income level (say, top 5%-3%) I intended to be around 100%. I thought basically 100% of the top of the top attended college, but for me being in the top 5% of income would have assured that. It's not like measuring "graduate degree" or something else. A college degree is quite standard for children of the top incomes. I also thought it would stop levelling up because some people from extremely rich families produce lazy children by spoiling them. If your child doesn't go to college when you're making $150,000, they're not going to go to college when you're making $200,000. If they're not going to go when you're pulling $1M per year, they certainly aren't when you're pulling $5M per year. (in fact might be slightly less likely to.)

As you can see from the rest of the album - http://imgur.com/a/hjvdf - I did quite well. But these effects aren't present at all.

Some of the poor attended exactly as I predicted, and this rose immediately with income. The effect I predicted that did NOT appear is that in the middle class, there is a firm distinction between being at the 40th or 60th percentile - it is still linear. I would have thought it didn't matter. If you look here - http://blogs.marketwatch.com/encore/2014/10/02/incomes-are-m... - sadly they only show a few select percentiles, but let's go around the $51,939 level at 50%. That is let's say $3,100 per month take-home pay, give or take. I wouldn't have expected there to be a huge decision on whether YOU will attend college, depending on whether YOUR FAMILY is earning $2,800 per month or $3,500 per month. Essentially, I think this wouldn't figure into your decision at all, period. Also, I think that being at the 40th to 60th percentile does NOT mark a shift in cultural status (what part of the middle class you're in), and also is incredibly fluid. A family's income could easily shift by this amount from one year to the next - what, would their child not attend college in 2003 but would attend in 2005, because they're taking home $3,500 per month instead of $2,800? Maybe to some small extend, but certainly not linearly.

So I expected a smooth or levelled-off part in the middle percentiles. This didn't happen, but the supplied point helped me avoid it - I actively adjusted my graph due to it.

I wonder what the reasoning was behind giving people a supplied point. I guess they wanted to know the shape people guessed, rather than the levels people guessed? Or set people's expectations, so that they don't have wild expectations about the percentage of the population that attends college?