Taking tests

sorabji.com: Why I oughta...: Taking tests

Rhiannon on Monday, September 27, 1999 - 04:01 pm:

    I know there are very few students on this board at the moment...but if you don't currently relate, I'm sure you remember having these experiences.

    I'm taking a quiz right now. It's due in an hour. I'm almost done, except for one problem, and you're going to hear about it since I have no one else to complain to. Here it is:

    5. Tom gets a 650 on verbal SAT and a 750 on math SAT. Assume the standard error of measurement is 30 for the first test and 40 for the second.

    a) Would we be justified (certain at the .05 level) in concluding that Tom is more able in Math than in Verbal ability?

    b) What is the reliability (split-half, Spearman Brown corrected) of the Math test? What is the reliability (split-half, uncorrected) of the Math test?

    Well, fine and good, but A) we never learned how to do a split-half test, B) I'm looking in my book (it's an open-book quiz) and I can't find a corrected vs. uncorrected equation, and C) the only equation I can find is for estimated reliability and it requires you to know the obtained reliability, which is what I'm looking for in the first place!


    What am I supposed to do, huh? I can answer part A. (Yes, as the scores are greater than one standard deviation apart). But I think I've done really badly on the rest of the quiz, so I'm rather loath to leave part B blank, although if he said if our exam average is higher than our quiz average at the end of the semester, the quizzes won't count at all...

    I can't even attempt the equations, because they're the only ones I have, and yet I'm missing more than one variable, mainly because the SAT tests are NOT split-half tests! So how can you do a split-half test on them?!?!?

    This sucks.

By Nate on Monday, September 27, 1999 - 04:56 pm:

    the answer to A) is no.

    you're comparing apples and oranges. a point verbal is not equivlent to a point mathmatical.

By Rhiannon on Monday, September 27, 1999 - 05:24 pm:

    Shit. You're right -- there's nothing to say that the tests are parallel. I didn't even think about that. Looks like I fail another one.

By Agatha on Monday, September 27, 1999 - 06:18 pm:

    is this a logic class?

    while we're talking about tests, has anyone here taken the gre's? if so, what was it like?

By Semillama on Monday, September 27, 1999 - 06:33 pm:

    not too bad, if you prepare. Get one of those books, they get you used to what the trick questions look like.

    Rhi, it's probably too late, but for the second question fill in why you feel you can't answer, maybe that's the correct one.

    unless you missed that day.

    Anyway, I took the ACTs.

By Rhiannon on Monday, September 27, 1999 - 06:48 pm:

    I did just what you suggest, Sem.

    Agatha, it's a class in psychometrics (basically, the mechanics of IQ and personality tests...lots of statistical math). I have to take the GRE's in November...actually, I have to sign up for them this week as the deadline's 10/1. One more thing I have to do. (Oh, yeah, I'm not looking forward to them at all).

    I took a class in logic my freshman year. Failed it, too...the only class I've ever failed. The first few weeks it was all verbal syllogisms ("Mary is smarter than Bob. John is smarter than Mary" etc). THEN, as soon as it became too late to drop the class, it suddenly became all geometric logic from that point on ("Given point y is between point x and z, prove points x y and z form a line" or something like that...). It was a lot more involved than that, but if I could remember it now, I would have understood it then. (How's that for logic? :) )

By Fetidbeaver on Monday, September 27, 1999 - 06:51 pm:

    Here's a question for you.
    You build a square house.
    All the outside walls face south.
    A bear knocks on the door.
    What color is the bear?

By Waffles on Monday, September 27, 1999 - 06:52 pm:

    do like i did when i wsa too hung over or completely failed at doing my homework....if it's a scantron test or quiz.......turn the narrow answer sheet horizontal and spell out "ozzy rules" in the bubbles...your professor will be most impressed

By Waffles on Monday, September 27, 1999 - 06:54 pm:

    null and void
    they do not acknowledge our human custom of "knocking" therfore his color is irrelavent.

By Fetidbeaver on Monday, September 27, 1999 - 06:59 pm:

    This is a very polite bear. NOW ANSWER THE QUESTION.

By Rhiannon on Monday, September 27, 1999 - 07:01 pm:

    I love bears. Hopefully, it is a big fuzzy *brown* bear. Am I right?

By Fetidbeaver on Monday, September 27, 1999 - 07:03 pm:


By Rhiannon on Monday, September 27, 1999 - 07:03 pm:

    No! I get it. It's a white bear.

    But maybe he has a brown friend with him...

By Fetidbeaver on Monday, September 27, 1999 - 07:04 pm:

    He is white, but why?

By Rhiannon on Monday, September 27, 1999 - 07:07 pm:

    The house is built on the north pole, of course.

By Fb on Monday, September 27, 1999 - 07:08 pm:

    DING DING DING we have a winner.

By Nate on Monday, September 27, 1999 - 07:11 pm:

    he could be blue.

    what if there was a traveling circus?

By Swine on Monday, September 27, 1999 - 07:36 pm:

    what if i was hanging out in that little north pole loveshack with santa claus and his little elves, knocking back obscene amounts of tequila shooters and getting all geeked-up on high-powered psychedelics and devil's dandruff? huh? goddamned polar bears could be any color in the rainbow... not to mention the giant bats and flying monkeys... you're logic doesn't work here, man. you can't judge me. we're beyond good and evil up here in our little love shack. it's all about diametrics, man... diametrics...

By Waffles on Monday, September 27, 1999 - 07:37 pm:

    .....uh yeah and he missed the bus and he is stuck in anchorage and he is looking to work for food.....circus bears have little or no natural survival instincts you know but they can sure as hell ride a motorcycle

By Fetidbeaver on Tuesday, September 28, 1999 - 12:37 am:

    Swine, if you find this north pole party palace I want directions.

By Gee on Tuesday, September 28, 1999 - 04:27 am:

    Leave Santa alone. You're not too cool for a spanking, mister.

By J on Tuesday, September 28, 1999 - 09:58 am:

    I was in a love shack once,Santa gave me lots of "presents".Polar Bears are the biggest bears in he world.

By Simon on Tuesday, September 28, 1999 - 10:53 am:

    Let's consider this a moment:

    First, picture in your mind the world's largest and fiercest land-dwelling predator, the polar bear.

    Now, put him on a Harley on the streets of Anchorage, where there happens to be a ratio of one tavern for just about every 1.8 human beings.

    Just be happy that circus bears don't drive semi's, or he'd be making a road trip back up to the love shack to bring his buddies down for a poker run.

By Waffles on Tuesday, September 28, 1999 - 11:59 am:

    polar bears and SUVs........there's strange metaphorical contrast

By Rhiannon on Wednesday, September 29, 1999 - 06:49 pm:

    Got the quiz back today...I got a 3.25 out of 9 on it! Hee hee! Good thing they don't count. I knew why I made so many mistakes -- mostly because I didn't answer the questions at the level he was looking for, or I would only give part of the answer. Ack.

    You were right, Nate, about, um, what you said...the answer was no. But not for that reason. It was for some weird reason, like the standard error of measurement for both tests include different errors, so the true scores aren't necessarily the ones up there...or something...I wasn't paying attention.

    Unfortunately, we all have to redo that question for Friday. So I'd better figure out that formula real fast.

By Nate on Wednesday, September 29, 1999 - 07:53 pm:

    that's what i said. i just said it different.

    math knowledge and verbal knowledge doesn't quantitate the same. a point of SAT math knowledge does not refer to a percentage of the total math knowledge that is the same as a point of SAT verbal knowledge as a percentage of total verbal knowledge.

    philosophically, the set of math knowledge is greater than the set of verbal knowledge. the subset of math knowledge that the SAT tests is a considerably smaller percentage of the total set of math knowledge that the subset of verbal knowledge is of the total set of verbal knowledge.

    in addition, if you take the whole of test results you can determine a percentile that each test score will fall into. equal scores in each of math and verbal will not fall into equal percentiles.

    i blame god.

By Fetidbeaver on Thursday, September 30, 1999 - 01:01 am:

    What about te polite white bear?

By Fetidbeaver on Thursday, September 30, 1999 - 01:02 am:

    Better yet, what about THE spelling.

By friendly on Thursday, September 30, 1999 - 01:19 am:

By Rhiannon on Friday, October 1, 1999 - 03:11 pm:

    I understand the math now. The following should not be read by anyone except those who need the math:

    To do part A) What you're looking for is the sampling distribution of the differences, also known as the standard error of the differences. What you have are two observed scores for Tom. You want to know if the difference between the scores would stay the same/change if Tom took the two tests a million times. So here's what you do:

    To find the standard error of the differences, you take the square root of (the variance of the errors for test 1 + the variance of errors for test 2).

    In this case, that would be the square root of 300 (30 squared) + 1600 (40 squared), which would give you the square root of 2500, or 50. Because 50 is half of 100 (the standard deviation of the means of the tests), you know that the results are not significant at the .05 level. (Look at a chart of t scores for an accurate significance value.)

    Part B) Okay, in the real world, you ONLY know the reliability for split-half tests. In this question you ONLY know the reliability for the whole test, so things are a little backwards. The uncorrected reliability formula gets you the split-half reliability, the corrected formula gets you whole-test reliability. We in this case have to work backwards.

    So, to get corrected/whole test reliability...use the formula that gets you the standard error of measurement. That formula states that the SEM is equal to the standard deviation times the square root of 1 minus the reliability coefficient. In this case, we have the SEM and the SD, so it's just a matter of solving for r. So:

    SEM = SD (square root of 1-r)
    40 = 100 (sq.rt. of 1-r)
    .4 = sq.rt. of 1-r
    .16 = 1-r
    -.84 = -r
    .84 = r

    Now, knowing that, we can do the uncorrected reliability coefficient: R = {length of test adjustment [called n] times correlation of split-half test differences [called r])/1+(n-1)(r)}

    So, in this case: R= (.5)(.84) / 1+(.5-1)(.84)
    It's .5 in the numerator because we're taking the split HALF of the whole test. This gives us an R of .72. It makes sense that the reliability of the split-half test should be less than the reliability of the whole test, because as you increase the length of the test, you get more of a chance for the errors to average themselves out.


By J on Friday, October 1, 1999 - 03:56 pm:

    Are you kidding?Me?Ha ha!!!!

By Foolioboy123 on Saturday, February 19, 2005 - 08:05 pm:

    i agree diametric maaan diametrics...........................ya
    you love us or you hate us.
    ive seen a snail crawl along the straight edge of a srarp
    razor. ive seen a snail slither along the straight sharp edge
    of a razor blade....and live.

    these are my dreams these are my nightmares

By Amil on Thursday, February 9, 2006 - 07:29 pm:

    ahh! i luff jew.


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