Sigh...

Let's say scores of the sample are

18 <---WB's ^_^ 84 78 74 79 96 35 78 85

sample mean (simple average) = 69.66....

standard deviation = 25.61738

Let's take out WB's score. This gives us:

sample mean= 76.125

standard deviation = 17.91597

Well lo and behold, while the average did increase by taking out WB's IQ score, the standard deviation ended up decreasing. This was because WB's sore was so low that it taking it out made the distribution more clumped together which results to less variability which means less sd. That is why you can't say that a sample's average score would increase/decrease by a standard deviation when you take out an element of that sample. It's not right to use sd in a sentence such as:




This was what I meant, nothing more, nothing less.

Just had to comment, my inner statistician was screaming murder. >.< Anyway, you can still have the last say after this post. :) Be my guest. :D

EW, you want to claim that I'm stupid? Go right ahead--it only proves YOU to be the idiot, especially with your twisted need to type childish symbols in nearly every post.

We're still waiting on your evidence to support your accusations against me, little man! Are you a man at all, or a giant lie with skin?

i think i finally understand your confusion. you think that the SD of the readers matters, as demonstrated in your example calculation, but no one cares about the SD derived from the IQ's of the board readers. that would never be used in a comparison or any discussion about IQ. the only SD that matters is the one that the test was normed to. that's the block of evidence you keep ignoring.

for Wechsler, it's 15, for Stanford Binet it's 16, for some others it's even 20 or 24. the actual number doesn't matter until you pick a test. the standard deviation that the test is normed to is essential to comparative measurement and is always considered when evaluating a test score. 100 is the average IQ of the population. so when you get your iq test, you can see how you much up against the rest of the population. since IQ is a bell curve, the SD tells you how close to the middle you really are.

let's say the board had four readers: Joey, WB, EW, Margie. All four take Wechsler's Assessment. Their IQ's according to the Wechsler Test (100 = average IQ, SD = 15) are as follows:

Joey: 2
Margie: 60
EW: 110
WB: 120

The Mean of the 4: (2+60+110+120/4) = 73
73 is roughly 2 standard deviations from the average (100) b/c the SD = 15 according to the TEST, not the population. not smart.

Take out Joey, the mean of the remaining readers is (60+110+120/3) = 96.66
the average for the test is still 100, the SD is still 15, period. pretty much average.

the collective IQ of the readership of the board just jumped up over 23 points, which is over 1 standard deviation... making my comment...



both grammatically correct and true. julie got it, why can't you see that?

Since you asked:



So when you say:



How does the "increase" occur? I know that you are pertaining to the fact that 73 jumped to 96 and the difference between the two is roughly 2 population deviations, but saying that the score "increased" in this manner is incorrect where statistical terminology is concerned. Won't explain it all over again. >.< Good night. :)

Evidently, the MORON who called me a moron for lack of anything brilliant to write, DOES NOT UNDERSTAND the definition of deviation. Lack of comprehension, eh? Didn't you know that it takes a 140 IQ to understand the complexities of mathematics?

And her pigheadedness is amazing, it's almost brilliant if it weren't moronic.

My guess for the posters IQ here would be:

Margie: 140
EW: 140
JULIE: 120
WritersBeware: 100
Lavinia: 84

Take a guess who got the lowest? I'm quite generous as it is.

Here's a hint, Lavinia: when you try to defend a mathematical ehrm, error, you don't use too much words. Only stupid math posers do that. The real math geniuses would understand an explanation without the verbiage. Have you seen how theorems are proven?

Hahaha, you're actually bothering to explain it? You're a saint. Ops! Now, I'm going to get accused of defending you -- the proven crook. ",)

"How dare you call a crook a saint?" "You are in league. You are paid by these fraudulent writing companies." And so it goes...

Buh-bye. Don't get too pissed. I'm not really serious about EW being a saint. :D

you answered your own question, good job!



you're awfully cocky for an individual who either 1. lied about her teaching credentials or 2. is attending a crappy school that lets individuals with undergraduate degrees teach other undergraduates. so it's taken you three years so far to work on your masters... will you be finishing it before the end of this decade?


your guess is way off. i've taken an IQ test, have you? since you still don't understand the way standard deviation works to evaluate the IQ test... i'd guess no.

you are so far behind the conversation that the 60 fits. you skipped all the evidence explaining the standard deviation of IQ tests. ouch.

Lavinia

Your post would have been far easier to read if you had stated that the mean IQ of the forum would increase if Joey were to leave. You caused confusion by stating that the IQ would increase by one standard deviation, thereby implying that the standard deviation would alter. This was not just my reading of the way this sounds but also of my daughter who is studying this at Uni. It is also obvious from the other postings on this subject that others have read this as a suggestion that the SD would increase.

Your assumption of an SD of 15 was based on Wechsler and as you have since pointed out other such experts have come up with varying different amounts for the SD in IQ assessments. You also implied in one of your posts that Stanford-Binet used the same formula but have since corrected this in the above post when you state that Binet assumes an SD of 16.

According to Wechsler the mean IQ would not change regardless of the presence of Joey or not as explained in my earlier post. Wechsler assumes a mean IQ as 100 regardless of the number of people tested. Therefore removing one from the test cannot impact on the mean IQ since the number tested has never been specified.

Lavinia

Your comment about a masters degree not taking 3 years to complete may be true in the US however in the UK a masters degree is for 3 years as standard and a PHD is for 5. It is likely that the length of time to complete a degree can vary form country to country. It is possible in the UK to take 5 years to complete an undergraduate degree if you are doing it as a part time student and in the UK once you have passed your undergraduate degree you are entitled to lecture at university so long as you achieved exceptionally high scores in your degree such as a first class degree with honours.

i'm not responsible for making my posts easy to read. you will encounter texts in your life far more difficult to read than my posts.

if my post wasn't clear to you, the appropriate response would be to ask for clarfication, not attack me.



it doesn't imply that to anyone with decent reading skills. i clearly said the IQ would increase; i didn't comment on the standard deviation size. stop reading posts at 5 am.



i said the collective IQ of the readers of this forum would change, not the mean IQ as determined by Wechsler's test. you agreed with me in your last post that this would happen.



even now, when it's clear that you posted completely backing me up, you don't confirm that and correct Margie or EW. could it be you are blinded by a personal dislike of me? can it be that you aren't objective AT ALL?

you don't know where margie is going to school. i actually did a bit of research on the web and found how long it takes to earn a masters in the country she identified. yes, 3 years is above average. why are you butting in now?

trolling for that shot to bring me into the "lawsuit"? do you really think it is appropriate to talk to me after legally threatening me? is that a how legal professional behaves in the UK?

btw, i personally believe that your attempt to use your daughter's supposed "stats knowledge" as a means to discredit me publicly is really poor taste. what a way to use your child as a tool to further your personal agenda. that's just my opinion of course, and I get to share it.

I tend to be on at 5am just before going to work and I find that the best time of the day for reading files for court as my concentration tends to lag by the afternoon as the office becomes very stuffy and noisy when all the other members of staff arrive.

Yes your post does say the collective IQ will increase but then you go on to put BY ONE STANDARD DEVIATION. This is just a flowery way of saying 15 or whatever you are assuming the standard deviation to be. I suppose you think it makes your post look smarter by being able to use the term standard deviation instead it provokes all this angst with people making assumptions that you are stating that the SD will increase.

I did say at my first post on this topic I was not familiar with SD and that my daughter had to explain it to me, and quite frankly it is hardly likely to have an earth shattering impact on my life now that I know what it means and how it is calculated. The point of my post was to highlight the confusion your post was creating by the way in which you expressed yourself. Quite frankly I do not give a fig about the impact of anyone leaving the forum and realise that this was your attempt at humour, however trying to make the post sound more authorative by using the term SD the impact of the 'joke' was missed completely. For posters on here that have no clue about SD they might not have even worked out that you were insinuating that Joey's IQ was 15 until you explained yourself in later posts.

should i point out that you've only responded with words? it just seems too easy.

or that this is the root of my frustration (if this wasn't so funny... or fun). yes, my statement required a little bit of thought. that's not a crime.

Actually it was her idea that I should post not mine and I hardly think that at 19 she is a child. As for me taking any legal action against you this has never happened and I was merely cautioning you against defaming me, though I would hardly waste my time in bringing such an action for a mere comment on an internet site. That was what you might class as a gut reaction to the accusations that I was a liar etc.

I was not attempting to suggest that Margie was telling the truth about how long an MA would take to complete I was merely pointing out that different countries have different timescales for these courses to be completed in and that in the UK a newly graduated student is allowed to teach other undergraduates.

the only people suffering from "angst" are people with an axe to grind with me personally. EW posts to support Joey consistently and i humiliated him with the ad hominem discussion. Margie is clearly an ESL writer with a chip on her shoulder and wanted to accuse me of racism. Apparently, EW and Margie think it's more important to defend sexist morons than it is to be ethical or factually accurate.

And then there is you. The queen of promising evidence that never delivers. i've called you out a few times on that. you've threatened me with legal action. what a shock that you decided to jump in even though you know nothing about SD's. except you looked totally foolish because in your attempt to prove me wrong you actually backed up everything i'd said.

again, anyone who was unclear could have asked for an explanation. that's not what happened. instead, you, EW, and Margie post blanket assertions with zero evidence or contextual understanding of the role of the IQ test determined SD that I was incorrect.



SD isn't brain surgery. It's not rocket science. People like you and Margie need to stop mystifying the math likes it oh so difficult to understand. it's not. SD is a stats term that every college first year student should know. if you haven't been graded on a curve, then you haven't really experienced the height of competitive academic rigor. take an honors chemistry class where the final mean is 40 out of 100 and the SD is 5 and see if you can pull off an A. now that is fun! if you earned a master's or phd and weren't required to take a stats course, then you attended a crappy school, whatever country you live in.

this is an academic forum frequented by individuals claiming to be qualified to write for an academic audience. and yet the posters freak out when a comment actually requires a bit of thought and math knowledge. it's sad and irresponsible... and well, a little bit funny.

Since when would a barrister ever need to know about SD? It is hardly likely to come up as a question form the judge

'Do you think your clients IQ deviates from the norm by more than one standard deviation?'

I can really see a judge uttering that (not)

Maybe in the US SD is taught as part of the curriculum. In the UK it would only arise if you were taking a subject such as A level Maths or Psychology or Chemistry none of which are required elements to study law. Law graduates tend to do A levels in English and History as these are usually required to be able to get a place at university.

I guess also it depends on how long ago you were in education as I completed school quite a long time ago before the advent of GCSE's. At least I was honest enough to admit my lack of knowledge of SD. I did not pretend to know anything on the topic and was merely posting based on the information supplied by my daughter who does know about this topic.

well, that is a shame and an academic mistake that should be corrected by the system. understanding statistics can and should make you or anyone a more competent barrister. and frankly, it's knowledge that should be attained for non-professional reasons. maybe i am just old fashioned, but i'm a strong proponent of liberal arts educations where individuals pursuing any degree should be able to demonstrate competency in other subject areas. an individual with an English or Law degree SHOULD understand SD just like an Engineer SHOULD have a grasp of history and literature. and frankly, everyone should have firm background in the sciences b/c that's just basic understanding about the world that anyone should know.

Be this as it may in the UK subjects are taught in terms of what will be needed for that person to pursue their given career and as mentioned above it is highly unlikely that a barrister or law student would ever be required to calculate the SD of any variable.

As I am a perpetual student (my husbands term for me) I am constantly enrolling in new courses in law which would probably bore the socks off most people. I lecture in law on occasion as I enjoy the challenge of imparting my knowledge to others and I also assist at the law school when students are required to practice their negotiation skills as part of their course. Its a bit like acting without having the cameras there (tongue-in-cheek)

By the way I did attempt to post my evidence on student cheating last night (which has been labelled in the UK as contract cheating) but was having technical difficulties with my computer (it kept crashing) and have noticed that the post has not been added. I have saved the websites on my computer and so will repost the evidence after I have cooked tea as the natives here are becoming hostile demanding I feed them.

You are just mad because under my suggestion, your rude self would be removed. Then the rest of us would not have to put up with such spiteful rudeness.

I suggest that your demeanor would be greatly improved if you took a very long walk off a short pier.

You are not the all knowing all seeing all great writer, either. So quit being all high and mighty, oh great Essay Writers (as in, crap company that doesn't pay real wages and then doesn't pay at all) writer.

PS: Who gives a flying crap what the SD or collective IQ is or would be? IQ doesn't mean jack.

PPS: Some of you should be ashamed of yourselves. If my children talked like you they would get a good old fashioned swat on the butt. Didn't your parents raise you to respect other people while expressing an opinion, or are you just vapid animals?

Grow the frack up.