# What "simple" academic concepts have you never been able to grasp? **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [March 30, 2009, 9:32pm UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355 "2009-03-30T21:32:07Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [March 31, 2009, 2:42am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/41 "2009-03-31T02:42:00Z")
> [@Indistinguishable](#): > > Alright, time for me to actually contribute something to this thread. I have a terrible time grasping statistics… by which I mean, it always seems to me that what’s being calculated is backwards from what I’d actually want to know. p-values, confidence intervals, and so forth. I toss a coin heads fifty times in a row and then say “Hm, I wonder if this coin is weighted”, so I go off and compute a p-value, something like “What’s the probability of a coin coming up heads fifty times in a row, given that it is unweighted?”. But that’s not really what I want to know! I want to know something more like “What’s the probability that a coin is unweighted, given that it comes up heads fifty times in a row?”… it seems like the practice of carrying out the former calculation is just based on erroneously conflating it with the latter one. And so it seems to me with practically every other major statistical tool; it seems like it’s all based on very elementary mistakes concerning conflation of converse conditional probabilities. And yet, it’s a large field, filled with presumably intelligent people who are all quite familiar with this concern and have a fine response ready to give. But it still hasn’t come to me… You’re interested in is [Bayesian inference](http://en.wikipedia.org/wiki/Bayesian_inference). ---
**Author:** ![matt\_mcl](https://avatars.discourse-cdn.com/v4/letter/m/7ab992/32.png) [@matt\_mcl](https://boards.straightdope.com/u/matt_mcl)\ **Post date:** [March 31, 2009, 2:53am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/42 "2009-03-31T02:53:55Z")
> [@Indistinguishable](#): > > I see now that **matt\_mcl** , in his definition of “irrational”, made special exemption for a denominator of 1, but that’s unnecessary and doesn’t accomplish what I think was intended; you can still express π as (2\*π)/2, for example, and so on. Like I said, all the definition you need is that rational numbers are expressible as ratios of _integers_. You’re right. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 31, 2009, 3:07am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/43 "2009-03-31T03:07:30Z")
Quoth **Jragon** : > [@](#): > > Edit: The only thing in math i have real trouble with is my stupid 7 times tables, I don’t know if 7 and base 10 just don’t agree or what, but I hate hate hate multiplying by seven. 7 and base 10 just don’t agree. Everybody has trouble with the 7 times tables. In any base, the factors of the base have nice times tables, and the factors of the base minus one have nice times tables, and everything that’s a product of those has nice times tables. 7 is the only number less than 10 that doesn’t meet any of those criteria, so it doesn’t have a nice times table. > [@](#): > > You’re interested in is Bayesian inference. Right, and the reason why statistics doesn’t tell you the answer to the question you’re asking is because you don’t have enough information. Suppose you find that there was only a 1 in 1000 chance to get the sequence you got from a fair coin. OK, but how common are trick coins? If only 1 in a million coins is unfair, then even with your flukish result, you probably still had a fair coin. If, however, fair coins and unfair coins are equally common, then you could probably safely conclude that your coin is unfair. You need to have that initial estimate of the probability, called a prior, to answer that question. ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [March 31, 2009, 3:11am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/44 "2009-03-31T03:11:05Z")
Right, that I get; I understand that to satisfy my tastes I have to switch to Bayesian statistics and drown in the problem of the priors. What I don’t get is what frequentist statisticians think they’re doing; clearly, they don’t regard their own work as deeply mistaken, which leads me to believe that probably it isn’t. But what’s it doing, then? ---
**Author:** ![Maeglin](https://avatars.discourse-cdn.com/v4/letter/m/8baadc/32.png) [@Maeglin](https://boards.straightdope.com/u/Maeglin)\ **Post date:** [March 31, 2009, 3:51am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/45 "2009-03-31T03:51:43Z")
> [@Indistinguishable](#): > > Right, that I get; I understand that to satisfy my tastes I have to switch to Bayesian statistics and drown in the problem of the priors. What I don’t get is what frequentist statisticians think they’re doing; clearly, they don’t regard their own work as deeply mistaken, which leads me to believe that probably it isn’t. But what’s it doing, then? This is a massive subject, and one that my favorite quantitative methods teacher called “theological”. The [wiki entry](http://en.wikipedia.org/wiki/Probability_interpretations) is a decent start. Thank you for the Lockhart article. I was somewhat “math phobic” growing up: although I did well enough with the advanced/AP sequence, I did it despite autonomic unpleasantness (terrible anxiety, sweaty palms, accelerated heartbeat, etc) and thus very inconsistent test results. I did not truly discover mathematics until, of all places, grad school. I lament the lost time and have tried since then to make up for it. There is so much now that interests me, but picking up standard textbooks on my own has met with extremely limited success. I think I must be the one crazy person who was an indifferent equation solver at best (I can hardly help misplacing signs and other unforced errors), but good lord, I could spend hours tinkering with a proof or struggling to express a real-world process into game theoretical mathematics. I could spend my life doing that. ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [March 31, 2009, 4:02am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/46 "2009-03-31T04:02:53Z")
Hm… one other thing that I don’t know, I suppose, is what the connection is supposed to be between “frequentist” and “Bayesian” statistics and frequentist and Bayesian interpretations of probability, respectively. (Is there a connection?) Well, maybe this thread isn’t the place for getting the full lesson; I should perhaps start another… ---
**Author:** ![Infovore](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/infovore/32/420_2.png) [@Infovore](https://boards.straightdope.com/u/Infovore)\ **Post date:** [March 31, 2009, 4:04am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/47 "2009-03-31T04:04:03Z")
I like to think I’ve got a pretty decent vocabulary, but for some reason I can_not_ remember the definition of the word “tautology.” People explain it to me, I look it up in the dictionary, I get it…until next time I encounter it and then I’ve forgotten it again. I used to be this way with “aggregate,” too, but I’ve got that one down. I keep hoping I’ll have another epiphany. It’s embarrassing. ---
**Author:** ![Maeglin](https://avatars.discourse-cdn.com/v4/letter/m/8baadc/32.png) [@Maeglin](https://boards.straightdope.com/u/Maeglin)\ **Post date:** [March 31, 2009, 4:11am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/48 "2009-03-31T04:11:12Z")
> [@Indistinguishable](#): > > Hm… one other thing that I don’t know, I suppose, is what the connection is supposed to be between “frequentist” and “Bayesian” statistics and frequentist and Bayesian interpretations of probability, respectively. (Is there a connection?) Well, maybe this thread isn’t the place for getting the full lesson; I should perhaps start another… Please do. Although my job description says “statistician”, I am definitely not a capital-S statistician. I might have something to contribute, but even more to learn. > [@](#): > > ``` > I like to think I've got a pretty decent vocabulary, but for some reason I cannot remember the definition of the word "tautology." People explain it to me, I look it up in the dictionary, I get it...until next time I encounter it and then I've forgotten it again. > > ``` It might help to think about it this way. The part of the word “tauta” means “all” or “every”. If you can remember that, you can probably remember what a tautology means in formal logic. ---
**Author:** ![Nicolas\_Bourbaki](https://avatars.discourse-cdn.com/v4/letter/n/ecc23a/32.png) [@Nicolas\_Bourbaki](https://boards.straightdope.com/u/Nicolas_Bourbaki)\ **Post date:** [March 31, 2009, 4:39am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/49 "2009-03-31T04:39:09Z")
Volts. WTF are they, and what makes them all that different from an amp? And how do watts figure into all this. Also, to the OP: push the back of your hand against the bottom of your chin gently, and say the word out loud. The number of times your chin bobs down is the number of syllables. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [March 31, 2009, 5:02am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/50 "2009-03-31T05:02:15Z")
Calculus is pretty much where my brain called it quits. I got to the point where I could push my way through it by rote memorization and brute effort but it never really sunk in. ---
**Author:** ![placebo](https://avatars.discourse-cdn.com/v4/letter/p/e274bd/32.png) [@placebo](https://boards.straightdope.com/u/placebo)\ **Post date:** [March 31, 2009, 5:03am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/51 "2009-03-31T05:03:52Z")
Infinity. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [March 31, 2009, 6:23am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/52 "2009-03-31T06:23:57Z")
> [@Nicolas\_Bourbaki](#): > > Volts. WTF are they, and what makes them all that different from an amp? And how do watts figure into all this. One of the simplest ways to look at electricity is to compare it to water. Volts are like water pressure. Amps are like the amount of water passing a given point. Watts are kind of a combination of the two. Watts measure electrical power. Power is the rate of energy flow per unit time. To get the same number of watts, you can have a few amps and many volts, which is like a thin stream of water jetting out of a narrow hole at high pressure. Or, you can have many amps and a few volts, which is like a wide and deep river flowing slowly past under low pressure. In both cases, the same amount of energy is being transferred (the same volume of water is being transferred each second). ---
**Author:** ![bobot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bobot/32/21622_2.png) [@bobot](https://boards.straightdope.com/u/bobot)\ **Post date:** [March 31, 2009, 7:15am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/53 "2009-03-31T07:15:31Z")
Multiplying double digit numbers by other double digit numbers in my head. I write 'em down everytime. ---
**Author:** ![Leiko](https://avatars.discourse-cdn.com/v4/letter/l/c5a1d2/32.png) [@Leiko](https://boards.straightdope.com/u/Leiko)\ **Post date:** [March 31, 2009, 8:52am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/54 "2009-03-31T08:52:46Z")
> [@Chronos](#): > > Quoth **Jragon** :7 and base 10 just don’t agree. Everybody has trouble with the 7 times tables. In any base, the factors of the base have nice times tables, and the factors of the base minus one have nice times tables, and everything that’s a product of those has nice times tables. 7 is the only number less than 10 that doesn’t meet any of those criteria, so it doesn’t have a nice times table. When you say product you actually mean factor, right? I ask because beyond that, this is the most fascinating piece of math knowledge I’ve gotten in a really long time. I’ve always had trouble with my 7 times tables, to the point that I only know 6x7 because it’s 7 times 7 minus 7 (It’s easy for me to remember the squares.) And on the subject of math, I still don’t know how I got a C in calculus. I know that the derivation of x to third power is 3 times x to the second, and beyond that I know nothing about calculus at all. ---
**Author:** ![footballisplayedwithyourfeet](https://avatars.discourse-cdn.com/v4/letter/f/9f8e36/32.png) [@footballisplayedwithyourfeet](https://boards.straightdope.com/u/footballisplayedwithyourfeet)\ **Post date:** [March 31, 2009, 9:03am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/55 "2009-03-31T09:03:51Z")
> [@starwarsfreek42](#): > > Imaginary numbers. If you can imagine there’s a number there, you can imagine I got a B+ on this test. I will second that, didn’t get a B+ though; got a C and ran away as quickly as possible and never looked back. I’d rather remain ignorant and just say you can’t take the square root of a negative number!🆒 ---
**Author:** ![MeDrewNotYou](https://avatars.discourse-cdn.com/v4/letter/m/838e76/32.png) [@MeDrewNotYou](https://boards.straightdope.com/u/MeDrewNotYou)\ **Post date:** [March 31, 2009, 9:22am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/56 "2009-03-31T09:22:10Z")
Science is a breeze for me, as is math. But I utterly (and embarrassingly!) fail at languages other than English and Latin (and 2yrs of Latin were the hardest courses I’ve taken). For some reason, even trying to learn Romance languages is an effort in futility. That and getting “its” and “it’s” straight. No matter how often I hear what the difference is, 5 minutes later, I’ll end up guessing. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [March 31, 2009, 10:18am UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/57 "2009-03-31T10:18:14Z")
The only science-related subject I’ve ever had trouble with is electricity. I’ve gone through all of the helpful analogies, but I just cannot make my brain work it out. I had an entire semester of it in college, and the only way I passed was by just plugging in equations without understanding them. It was miserable. ---
**Author:** ![NicePete](https://avatars.discourse-cdn.com/v4/letter/n/ee7513/32.png) [@NicePete](https://boards.straightdope.com/u/NicePete)\ **Post date:** [March 31, 2009, 1:18pm UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/58 "2009-03-31T13:18:05Z")
> [@Reply](#): > > Gerunds. What the heck are they? Frustrating. If you’re still wondering, I could try explaining, but it might be too confusing. So I’m abstaining and refraining from elaborating on verbal noun-ing. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [March 31, 2009, 1:41pm UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/59 "2009-03-31T13:41:30Z")
I never learned to factor. I remember quite clearly not paying attention that day in Algebra II. I made a 5 on the AP Calculus exam doing six times the work because I had to fake backwards from what the calculator said to pretend I could factor. I was such a freaking dumbass. If I had gone to my teacher over lunch, like, ONCE, I’d have learned how. And I’m sure she knew, too. Not that it matters now, as I don’t remember a single thing about calculus except how points are awarded on the AP exam. ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [March 31, 2009, 1:55pm UTC](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355/60 "2009-03-31T13:55:51Z")
> [@eleanorigby](#): > > Pi, as in 3.14 etc. It’s used as a constant (and what is THAT?) in higher math (higher math to me meaning Trig, having never advanced as far as calculus). What is it supposed to do? WHY did I need it? And why did I need to know how to solve the quadratic equation? God knows I did my share of them, but WHY? I’m all for learning for learning’s sake, but not one teacher EVER put this stuff into any kind of a context for me. It’s in calculus (which I was never good at) where these things start showing their usefulness. You can use them to figure out how long it’ll take to fill or empty your swimming pool (god, why do I still remember that test question?) or whether the building or bridge you designed is going to collapse under its own weight. > [@Patch](#): > > Boy, I don’t hear that at all. No wonder I don’t understand them. Try saying “Hah” and “Hi” very slowly. “Hi” starts as “hah” but then glides into a different sound – haaaaaaaaeeeeeeeeee. You should be able to feel your tongue move as you stop saying “ha” and start saying “eeeee.” [Previous page](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355.md?page=2) [Next page](https://boards.straightdope.com/t/what-simple-academic-concepts-have-you-never-been-able-to-grasp/491355.md?page=4)