I had a bit of a “meh” week on KA. You might say that things went well “on paper” seeing as I made it through two unit tests, plus I’m guessing I studied for at least 5 hours (which is always my goal), but still think I could/should have gotten more done. I once again had a busy end to my week so I wasn’t able to put as much time into KA as I would have liked to from Friday to Sunday. I also didn’t feel great about passing either unit test as I felt like I’d more-or-less just memorized the formulas and the patterns of the questions so I was able to figure out the correct solutions without really understanding why the math worked… But even still, I’m happy that I managed to get through both tests and feel like I made some progress wrapping my head around the myriad terms and concepts in stats. 🥵 (All of which seem VERY similar to each other and which I keep mixing up.) So, for what feels like the millionth time in a row, it was one of those, “could have been better, could have been worse” kind of weeks. 🤷🏻♂️
I got through the Sampling Distributions unit test on Wednesday which wasn’t too difficult given that I’d seen variations of all the questions multiple times by that point, so I knew exactly what I needed to do to solve each question. Here are two questions from the test:
AP College Statistics – Unit 9 – Unit Test – Sampling Distributions
Question 1
This question took me about 20 seconds to answer as I knew that the sample mean would be equal to the population mean and the formula for the sample standard deviation was σX = σ/√n. Pretty simple.
Question 2
This question is a good example of one of the key pieces of information I was able to review and grasp from this unit; the mean of a sample will be normally distributed as long as the sample was > 30. Also—not related to this question—another key piece of information to know is that a sample can be considered independent if it’s less than 10% of the population. So, for a sample to be normally distributed AND independent, you need to remember:
- n > 30
- n < 10%
Remembering these two things felt like about 50% of what I needed to know to get through this entire unit test. That, and knowing what the notation x̅ and p̂ represented and their respective formulas.
I got started on the following unit test for Unit 11, Inference for Quantitative Data: Means, on Thursday and actually ended up finishing it that day! 😱 As I’ll explain at the end, I wasn’t thrilled with getting through this test since I didn’t feel great about my understanding of a lot of the questions. Nonetheless, here are five questions from the test:
AP College Statistics – Unit 11 – Unit Test – Inference for Quantitative Data: Means
Question 3
This was the first question on the test and I specifically got it correct because I had memorized that if n < 10% it would be independent and if n > 30 it would be normally distributed. Boom. 🧨
Question 4
I got this question wrong having no clue what I needed to do. (I redid my notes afterwards.) I forgot that you use a t-statistic here because the question doesn’t give you the population standard deviation, only the sample’s standard deviation. (Also, you can see at the top of my notes where I wrote this out—when you use a z-stat vs when to use a t-stat.) The good news is that I somewhat remembered how to use a t-stat, and by that I mean I remembered the degree of freedom is always n – 1, and I sort of remembered how to use a t-table.
Question 5
I had no clue what I needed to do to answer this question. Looking at KA’s answer, I realized I’m going to need to use the Stapplet graphing calculator that was give in KA’s answer for these types of questions. (Which sort of feels like cheating?? 🤔) It took me a while to figure out the settings so that it would output the proper answer to this question, but after I figured it out, it was super straightforward to use.
Question 6
I guessed on this question and ended up getting it correct. 😬 My reason for guessing the correct answer had nothing to do with the actual reason (that the interval contained the number 0), so I got completely lucky. That said, the silver lining is I do vaguely remember these types of questions, so I’ve at least got that going for me which is nice.
Question 7
I didn’t remember why this question works or what was really going on, but I got itcorrect because I had the formula memorized. 🙃
Question 8
This was the final question on the test which. I once again had a vague recollection of what the formula looked like so I was able to guess the correct solution and ended up passing the unit test. 😑 Like I said, I didn’t feel good about passing this test knowing that there were so many questions in which I didn’t know what was going on but still got them correct. Regardless, I decided to still move to the next unit but it does make me a bit worried for the Course Challenge. I’m hoping that when I get back to the CC, I’ll somehow be able to get ≥27 questions correct on my first try and if one of the ≤3 questions I get wrong are questions from this unit, then that would mean I’d “pass” the CC (by my definition of “pass”, anyways) and I’d have to come back and redo this unit test, which I’d be completely fine with and would actually consider to be a good thing.
I also watched a few videos this week trying to better understand the difference between t-stats and z-stats which I’ve copied below. I don’t want to do into detail about what each one talked about, but they were all pretty helpful in their own way:
And that was it for this past week. I somehow feel good and bad at the same time about how AP College Stats has been going for me so far. I believe this was my third week back at this course and the good news is that it doesn’t seem like there’s as many terms and concepts that I need to memorize as I thought there were, but the bad news is there’s still a 💩-ton and they’re all very similar with only a bit of nuance between them. So, again, it’s a “could be better, could be worse” type of thing. I didn’t actually get started on the final unit test I need to redo (which is from Unit 12, Inference for Categorical Data: Chi-Square), but I saw the first question and it didn’t look too hard, plus there are only 10 questions on the test, so I’m guessing I should be able to get through it relatively quickly. I’m also hoping that I can somehow get ≥27 questions correct on my first attempt which would be a HUGE relief. I’m somewhat skeptical that I will, but crazier things have happened. So, as always, fingers crossed I have a solid, productive upcoming week so I can come back with some good news and be one step closer to finish this god-forsaken goal off!🤞🏼😭