Scoring Algorithm

[Eitan]

Hi,

I just took a practice exam, and it seems like I'm getting some wierd results.

In class the way the scoring algorithm was described was you start out around 50%, if you get the question right you move up, if you get it wrong you move down. Fairly simple.

When I look at my results, sometimes the difficult level of questions doesn't follow what was described.

For example:

28 x Prob Solv Rock Paper Scissors 600 - 700 0:47 No Switch Probability
29 (Check) Prob Solv Fashion Faux Pas 700 - 800 1:25 No Switch Combinatorics
30 x Prob Solv Extracting X 600 - 700 2:06 No Switch Exponential Equations

28 was a 600-700 level problem. I got it wrong and it moves me up to a 700-800 level problem.

There were a few other occasions something like that happened. Any ideas?

Thanks,

Eitan

[StaceyKoprince]

Yes, we do talk about it that way in class to give you the general idea, but it's a lot more complex than that. The algorithm doesn't literally move you up or down based upon the last question only; it's more based on your collective performance to that point. The algorithm also has to manage some other things, such as the number of DS vs PS questions you get, and the number of questions you get in different content areas (eg quadratic equations vs. circles vs. rates).

You can also have a situation where your 600-700 question is a 690 and you get it wrong but you had some 700+ questions right before that, and then it gives you a "700-800" next that's actually rated a 700. There's not a huge difference in difficulty level there, even though it seems like it from the label. It's essentially saying - hmm, you got some other 700+ questions right but you got this 690 wrong - let me test you around this level again and see what happens. Oh, you got it right. Okay, now I need to give you a problem solving question from the exponential equations sub-group and the closest one I've got to your current level is this 680 problem right over here... so that's what you get.

In other words, it's not as black and white as it seems from the class 1 presentation. :)