@APmaster007 What? Isn’t a t test for sample data (such as sample SD)? If data for the population is given, use z test… at least this is what my textbook says and various online sources (http://www.differencebetween.net/miscellaneous/difference-between-z-test-and-t-test/). And thanks for the calculator!
@drakonus @picuberoot , Thanks. Yeah my teacher doesn’t know much, she was like “z-tests for proportions and t-tests for means”. But when I started using the Barons book, I saw it using z test instead of t tests on some problems that wanted the mean. So yeah, I guess when sd is given, I should use a z test. And also if the population is small ( less than 30), then it is a t test.
So does the frq always tries to confuse you between the two? Do you guys have any examples of questions from past years that did that?
wait if you want to make stat interesting you should try to actually derive some of the properties, curves, and all those numbers in the table in the appendix. for instance, if you want to find the equation of the normal curve (which approximates the binomial distribution), you do stuff like http://scipp.ucsc.edu/~haber/ph116C/NormalApprox.pdf.
@APmaster007 I personally haven’t seen any questions that try to confuse us using Z-test v.s. T-test, but there have been a couple of MC questions that make you choose what type of test to perform? What I’m most worried about is probability, I always get questions on that wrong 
Does anyone know if the pooled questions or paired t-test questions are on the exam? I’ve taken multiple practice tests and haven’t seen any.
@bayboi707 , look at last years frqs, one of them asked about a paired t test.
I hate this class :)))
Ugh, I felt really good about AP us history that I took today. Not looking forward to statistics…
I got 26/40 on the mc for the 2002 exam. I made so many stupid mistakes. How many are you guys getting right?
And are we allowed to use more than one calculator on the test?
same test i got 26 right
same i forgot dumb things like the outlier formula and the margin of error formula
@APmaster007
Guys please help. I thought when we know the standard deviation, we use a z test. So why for #4 on the frq of 2011, we used a t test? PLEASE EXPLAIN???
@APmaster007 I believe you’re confusing the standard deviation of a population with the standard deviation of the sample. The standard deviations given for group A and group B are standard deviation of SAMPLES (because group A and group B only contain a portion of all the males in the world). When you’re given standard deviation of a SAMPLE (most often notated as lower case s), you will use a t-test. When you’re given the standard deviation of the POPULATION (most often notated by σ), you will use a z-test. Like I mentioned earlier, when you encounter a problem that involves means (mean cholestrol level in your problem), you will almost 100% of the time use a t-test because the test writers will seldom write a question that involves a population standard deviation (refer to what I said a few posts ago).
@picuberoot , thank you. That helps a lot.
These are the following tests that showed up in past years frqs:
2014- paired t test
2013- test of independence
2012- paired z test
2011- two sample t test
2010- two sample t test
What do you think will be this year?
http://apstatistics.cmswiki.wikispaces.net/file/view/2002+AP+Stats+Released+Exam.pdf
can someone please explain #10?
@picuberoot
here, http://www.woodbridge.k12.nj.us/cms/lib010/NJ01913008/Centricity/Domain/515/2002%20MC%20Solutions.pdf
Can anyone explain when to use a 2sample test vs a paired one?
@harsh98 ,
You use a paired t test when you are comparing the same thing. For example, if you want to see who makes more money working in McDonald located in Times Squre, a husband or a wife? You want to compare the husband and wife in the SAME McDonald.
But if it asked if people who play sports could get in Harvard with a less GPA than people who don’t. Those would be a two sample, because the two groups are not related.
I’m not very good at explaining, but I hope that helped.
OMG, I keep getting in the mid 20s on the mc. How the hell am I supposed to score 30 or above on the mc?