np1 and np2 and nq1 and nq2 are all greater than 10, this is for tests with proportions.
Another condition is that n should be big enough so that the means of n are normally distributed.
Chi squared tests are used when there are two lists: expected and observed.
what test do we use for matched pair tests?
@Demonslayer1234 use a Paired T-Test… Take one pair and put them in list a, take the second pair and put them in list b, and subtract a-b for list c. Then run a t-test for list c.
This is the AP test I’m dreading the most. I’ve dreaded this more than AP Lit and even AP Bio. It looks like if you get a 20/40 on the MC and a 2/4 on pretty much every FRQ, then you’re set for a very solid 4, so that’s what I’m going to aim for 
I really want college credit because I don’t want to take this in college (it’s a nursing major’s ONLY math requirement!!)
I have to review the hypotheses tests/confidence tests because it’s all a big bag of jell-o in my brain. My teacher didn’t really attempt to organize the information, but I’ll admit that I definitely should have tried to do it myself.
And then there’s the fact that the formula sheet is basically sh*t, and so I have to put a whole bunch of them in my calculator, which I still have to figure out how to do :’(
@teiluuuj Um good luck trying to put formulas in your calculator. You realize they check your calculators and either make you clear all the data or put it in test mode so you can’t access anything you typed in before?
Also: anyone know if you’re docked points for wrong multiple choice answers? Or should you guess on everything you don’t know.
@catfanatic6 I’m pretty sure they actually don’t check calculators… My Stats teacher who seems pretty well versed with College Board’s policies had us put some formulas to calculate sample sizes in our calculator. And no, no points are docked for wrong answers. Better to guess on everything than leave it blank 
EDIT: So here’s College Board’s official policy: https://apstudent.collegeboard.org/apcourse/ap-statistics/calculator-policy. You can use programs for certain things (which happen to be the only things I have programs for), and it specifically states the memory will not be cleared.
@misterdjl Thank you!
i have a question lets say a variable D has mean of 120 and standard deviation of 15 and variable F has mean of 100 and standard deviation of 9. Both of the variables are independent. What would be the standard deviation of (D-F)? there has to be a way to do it because you can’t just subtract standard deviations.
Because the samples are independent, you can sum variances (even when you subtract means, you have to sum the variances). To calculate variance, remember that standard deviation is the square root of variance.
I’m really freaking out about this test…I don’t remember any of the concepts
@teiluuj @misterdjl But my teacher told us they would check our calculators and we have been putting our calculators in test mode for every test so far. Do different schools implement different policies, because not regulating the calculator memory is just asking for rampant cheating.
May I ask what type of calculator you have? Like it is a systems upgrade or is it notes? Because formulas for the sample size isn’t a program on my calculator…
@catfanatic6 I’ve got a TI-Nspire. You don’t need the programs for sample size since they can be calculated out by hand, but as there’s most always at least 1 sample size problem, my teacher had us program our calculators that problem can be done in seconds. Those are the only formulas I have programmed, though.
I don’t think different schools implement different policies, since all teachers are reading from the same script, and the policy about not clearing memory is specifically stated on College Board’s website. But I’ve taken all my exams at the school, so I wouldn’t know for sure.
@catfanatic6 calculators aren’t checked
when are the degrees of freedom even used?
@uncletim32 t-tests and chi-squared tests.
ok
oh and what are some formulas we need to know that aren’t provided? @catfanatic6 @misterdjl
The formula sheets are so useless, most of the confidence interval and tests for proportion/means aren’t on there (which are only formulas that matter)
@uncletim32 in addition to the sample size formulas you should know the probability formulas. Some of them are on the formula sheet, but some of them aren’t. I think those are the only big ones, IIRC. You certainly need to know some smaller formulas, too, like calculating residuals and df for t-tests, lin-reg t-tests, and chi-squared tests.
This review sheet looks to have a lot of helpful stuff on it: http://www.nwcsd.k12.ny.us/cms/lib/NY19000569/Centricity/Domain/164/_Review%20AP%20Stats.pdf