Probability and Statistics

[GSLeloo]

Suck major balls.

That is all.

[Back]

And thats a bad thing?

[GSLeloo]

Fine...

It sucks Klaive's balls.

[Back]

Probability and Statistics can tell you a lot about who you want to sell things to. Marketing.

[Mistomeer]

I liked stats, but I came out with a B and slept through class.

[GSLeloo]

So you understand variation and deviation and quartiles and all that shit?

[Kitsun]

Variation, deviation and quartiles are the beginning prob and stats stuff! Those're the eaaaaaasy parts.

[GSLeloo]

............THIS IS EASY

I spent 20 minutes trying to do the deviation and I still came up 1.9 wrong

[Kitsun]

Toss up the problem and we'll see if we can figure out where you're going wrong. Heh.

[GSLeloo]

Well that one I figure, I must've made a calculator error as I was entering the fifty thousand figures in.

But now I'm on percentiles...

Ok here's the thing, we have a set of numbers:
2.6 2.7 3.4 3.6 3.7 3.9 4.0 4.4 4.8 4.8 4.8 5.0 5.1 5.6 5.6 5.6 5.8 6.8 7.0 7.0

They want me to find the 15th percentile.

So since there are twenty numbers I did (20 * 15) divided by 100. I got the number 3.

So I go and count to the third number... 3.4 YAY. I look at the answer in the back of the book and it's 3.5 Why?

[Edited on 9-26-2004 by GSLeloo]

[GSLeloo]

Ok I SORT of see what they're doing. You get the number 3 and for some reason they're adding .5 to it. Why? And like I got 6.6 and they raised it up to 7. And again for getting the 90th percentile I got 18 and they make it 18.5

[GSLeloo]

As I yank out my hair I will add....

Ok it appears I am right. But where the number changes is right after you do the nk/100... and it's when you find the depth of the number. But I have no honest idea how to find the depth.

I heard this mean joke, it goes:

The chemist laughs at the biologist, the physicist laughs at the chemist, and the mathematician laughs at them all.

[longshot]

To find percentile, the formula is

(n+1)P/100

Where "n" is the number of data in the set, and "P" is the percentile you are looking for.

There are 20 numbers in your data set, so n=1.

You are looking for the 15th percentile.

(n+1)P/100

(20+1)15/100 = 3.15

The location of the 15th percentile is 3.15.

You can't just pick the third number... it is the third number PLUS .15 of the difference beteween the third number and the fourth number.

The third number is 3.4. The fourth is 3.6.

So, the answer is 3.4 + (3.6 - 3.4).15 = 3.43

That should be the answer.

[Psykos]

Longshot is correct.

[GSLeloo]

The formula our book gives is NK/100 N being the number of data in the set and K being the percentile. Even the book agrees to that point and makes it an even 3 in the answer k. But then it does the depth of it and somehow makes it 3.5

Is what you did a shortcut maybe?

[longshot]

No, it's not a shortcut.

(n+1)P/100 is the formula for position of the data you want.

I don't understand what you mean by "depth" of it.

I showed you how to do the problem. I just had a test on this.



[Edited on 9-26-2004 by HarmNone]

[Bobmuhthol]

Hahahahahahah. Probability and Statistics is a class for absolute retards in my school.

[GSLeloo]

And as I said Longshot, that may be what you just had a test on but what I am going to have a test on is the formula in our book. Here, I'll give you the steps for it so you understand what I mean.


Step 1. Rank the data.

Step 2. Find P# nk/100

Step 3. Find the depth of P#,

Step 4. Find P#.

And as little as that truly explains, those are the steps in the book. That is how they want us to do it and that is why I can't understand that in some cases they change the position from 3 to 3.5 and in others from 6 to 6.6 But the change occurs when they ask you to get the depth.


[Edited on 9-26-2004 by HarmNone]

[Artha]

Hahahahahahah. Probability and Statistics is a class for absolute retards in my school.

In my school, it's the class slackers take instead of calculus.

[GSLeloo]

We have to take this class as a CORE requirement and I had to take it for my major.

[GSTamral]

<<<
Well that one I figure, I must've made a calculator error as I was entering the fifty thousand figures in.

But now I'm on percentiles...

Ok here's the thing, we have a set of numbers:
2.6 2.7 3.4 3.6 3.7 3.9 4.0 4.4 4.8 4.8 4.8 5.0 5.1 5.6 5.6 5.6 5.8 6.8 7.0 7.0

They want me to find the 15th percentile.

So since there are twenty numbers I did (20 * 15) divided by 100. I got the number 3.

So I go and count to the third number... 3.4 YAY. I look at the answer in the back of the book and it's 3.5 Why?
>>>

Longshot is incorrect.
In basic statistical analysis, while the formula (n+1)/k is correct, the answer is not rounded.

If the division yields an in between result, the answer is always the average of the 2, in this case, the average of the third and fourth number.

The reasoning for this is because the numbers you have provided are tangible real numbers. If the analysis involved vector quatities, or mathematical expressions, you would round as he explained.

Analysis of Variances of Means: look that up and you will see all of the rules regarding tangible sample (non population) oriented testing rules regarding this.

[GSTamral]

<<<
Hahahahahahah. Probability and Statistics is a class for absolute retards in my school.
>>>

So that explains why you've been attending the class then?

oooohoooh burn

[Bobmuhthol]

Wow that is so funny and would be true if I were not taking a more advanced class than most sophomores.

[Tsa`ah]

Originally posted by Bobmuhthol
Hahahahahahah. Probability and Statistics is a class for absolute retards in my school.

With that logic, most of the medical field are absolutely retarded with their PhDs.

[HarmNone]

Thanks for the explanation, Tamral. I'm sure it helped Leloo understand better. It was, for instance, much more useful than two kids posting about who does what in their highschools. ;)

Now, let's stop with the insults so I don't have to delete (veiled or direct) any more posts, eh?

HarmNone

[longshot]

Originally posted by GSTamral


Longshot is incorrect.
In basic statistical analysis, while the formula (n+1)/k is correct, the answer is not rounded.

If the division yields an in between result, the answer is always the average of the 2, in this case, the average of the third and fourth number.

The reasoning for this is because the numbers you have provided are tangible real numbers. If the analysis involved vector quatities, or mathematical expressions, you would round as he explained.

Analysis of Variances of Means: look that up and you will see all of the rules regarding tangible sample (non population) oriented testing rules regarding this.

That makes sense.

Harmnone,

You can't have your cake and eat it too.

Either delete my entire post, including the help I was kind enough to give her, or leave it be.

It's nothing that I haven't said before.

[GSTamral]

<<<
Wow that is so funny and would be true if I were not taking a more advanced class than most sophomores.
>>>

Congratulations. You got decent results from a standardized test and you think it qualifies you to make statements about the validity of other classes. How's this one for size. I probably took your advanced sophomore class in 7th grade, so I guess by your logic, you're retarded compared to me. I guess I can live with that.

[Bobmuhthol]

<<You got decent results from a standardized test and you think it qualifies you to make statements about the validity of other classes.>>

Ahem.

<<taking a more advanced class than most sophomores.>>

I don't know how you read that as "got a good score on a test."

<<How's this one for size. I probably took your advanced sophomore class in 7th grade>>

You probably didn't, unless you somehow managed to take high school honors classes 3 years early.

P.S. No you did not.

so I guess by your logic, you're retarded compared to me. I guess I can live with that.

Assuming you weren't a dipshit

[GSTamral]

<<
You probably didn't, unless you somehow managed to take high school honors classes 3 years early.

P.S. No you did not.
>>>

Actually I was in Algebra 2 with Trig in 7th grade, and skipped precalculus to move into calc in 8th grade.

[Artha]

I'm in Algebra 2/Trig :(

[Bobmuhthol]

<<Actually I was in Algebra 2 with Trig in 7th grade>>

So you went to a high school in 7th grade?

I did, I could have started in 6th grade actually. Too bad high school sucked my nuts and I didn't take advantage of it.

[Tsa`ah]

Originally posted by Bobmuhthol
So you went to a high school in 7th grade?

Why not? I did. The HS was on the other side of the park. 8 of us regularly attended Bio, band, lit, and math classes at the HS.

Tamral, Tsa-ah and me all on the same side. (4th sign of the apocalypse)

[GSTamral]

I went to a private school in which the middle school and high school were in the same complex. Plenty of people took high school classes while still in middle school. That was the only way to get enough classes complete by 12th grade to earn an IB diploma unless you wanted to go to high school for an extra 2 years.

I got accepted into an IB program in the 5th grade, I got a 99.9 on the entrance exam, but I didn't want to go to school all the way across the city.

[Bobmuhthol]

<<Plenty of people took high school classes while still in middle school. That was the only way to get enough classes complete by 12th grade to earn an IB diploma unless you wanted to go to high school for an extra 2 years.>>

Making it not exactly as unique as, say, being 1 of 4 people to go to the high school in another town in 3 years and being ahead of 100% of everyone else.

[Latrinsorm]

Originally posted by Tsa`ah
8 of us regularly attended Bio, band, lit, and math classes at the HS. I've heard of kids going to advanced math, science, even English, but BAND?? WTF crazy New Deal was that a part of?

We could take Music , art and foreign language classes. I assume whatever program Tsa went through wasn't so different then the one I did

[Numbers]

Except that college math is VERY different from high school math (including the honors and AP classes.)

ProbStat was probably the most useful math I've ever taken. The rest, aside from algebra, was just a waste of my time.

[GSTamral]

IB Diploma > Going to high school 2 years early

IB Diploma >>> Going 1 year early

Going to High school early > Taking high school classes early.

Many people who can skip a grade choose not to due to the potential ostracization from social groups. Of the 815 other 7th graders who scored above a 1350 on the SAT (old test, would be a 1450 or so now with the curve) as part of the CTY study (back in 90-91), only a small fraction (less than 15%) of them actually chose to skip a grade.

Eh. My high school diploma means shit to me.

[Tsa`ah]

Originally posted by LatrinsormI've heard of kids going to advanced math, science, even English, but BAND?? WTF crazy New Deal was that a part of?

I wasn't a band geek unfortunately. Learning to read sheet music at the age of 31 isn't hard, but I've done easier things.

In Jr high we had 5 students that from the age of 5 had private lessons. In Jr high you have "band" as an option. These kids went to the HS for band because that made them elidgable for State competition. Not many HS graduates have 32 + first place wins and rankings upon graduation. Because of this we had one graduate recieve acceptance into Juliard (sp) and to into the Berkely School of Music.

I took Bio 1,2, Chem 1&2, math to trig, and 3 lit/english classes before my freshman year. Had I been interested in graduating early I could have done so after my first semester my Soph year. My Jr and Sr years were screw around time. I had 4 study halls back to back, Computer lab, 2 spanish classes, and work study for the last two periods of the day. All that in my last two years, not each year.

[GSLeloo]

So on topic here... I e-mailed the teacher as to why you change 3 to 3.5 and why 6.6 became 7. This is his reply.


Christina:

If nk/100 is an integer then add 0.5 to it to get the depth.
If nk/100 is not an integer then the depth equals the next integer.
This procedure is explained at the bottom of page 95 in the textbook.

[DeV]

Originally posted by Bobmuhthol
<<Plenty of people took high school classes while still in middle school. That was the only way to get enough classes complete by 12th grade to earn an IB diploma unless you wanted to go to high school for an extra 2 years.>>

Making it not exactly as unique as, say, being 1 of 4 people to go to the high school in another town in 3 years and being ahead of 100% of everyone else. Highschool is a cakewalk. College is where the real fun begins.

[GSTamral]

<<<
I took Bio 1,2, Chem 1&2, math to trig, and 3 lit/english classes before my freshman year. Had I been interested in graduating early I could have done so after my first semester my Soph year. My Jr and Sr years were screw around time. I had 4 study halls back to back, Computer lab, 2 spanish classes, and work study for the last two periods of the day. All that in my last two years, not each year.

>>>

Lucky you. The school I went to kept having more classes.

My junior year:

DiffEq
Statistical Geometry
AP Physics
AP Chem
TOK
IB Level 1 English/AP
AP German
AP/IB European History

My senior year:
Advanced Topics German/IB
TOK2
IB Level 2 English
AP Physics C E&M
AP Econ Macro+Micro
Teaching Assistant for AP Physics B to get a sixth required class

Although we didn't have study halls for upper classmen, just free periods, which I did have plenty of.

Although I will say vector calc was by far the hardest class I've ever taken. Not like any of the classes were necessarily difficult, but some private schools will always find a way to keep students busy.
And its difficult to doze off in a class when you're the only one, or one of 3 people taking it, and the professor hasn't taught or studied the material in years.