2008 First Semester STATS课程官方问答贴

spirithell

Hi we did not learn that in chapter 10 or 11  !  I promise.

I think the exam for S1 2007 is more difficult than S2 2007 ( I did it before).

who else can i ask for if I got more question?  Tutor Room  or ...

ATM , you are GAY? OR LALA?

spirithell

who is the girl for tutoriual at room 120?

z-score

原帖由 spirithell 于 2008-5-28 17:41 发表
Hi we did not learn that in chapter 10 or 11  !  I promise.

I think the exam for S1 2007 is more difficult than S2 2007 ( I did it before).

who else can i ask for if I got more question?  T ...

WTF, ATM is my name, I'm not gay.

Yes, the exam in the first semester is usually a tiny bit more difficult than in the second semester. Yeah, if you have heaps of question, you can go to the assistance room and ask my sister Verina, the one with really straight hair and glasses.

spirithell

assistance room ?  Where? open Time?

如果过我在EXAM中牺牲了，您能不能证明我是个好学生？

或者为我做点别的事情， 不我救回来？

我已经做到16题了，真难~~~~~需要非常非常细心~~~~

眼睛大都花了~~~


cell contribution = (observed - expected)^2/expected

Try this formula.
没学过！！！！！！！

[ 本帖最后由 spirithell 于 2008-5-28 18:11 编辑 ]

spirithell

The standard error of the difference in sample means

what is mean of this above?  what the fomular can i use?

z-score

原帖由 spirithell 于 2008-5-28 19:18 发表
The standard error of the difference in sample means

what is mean of this above?  what the fomular can i use?

Formula sheet, under applications, number 3, difference between two means, se(xbar1-xbar2) =.......

z-score

原帖由 spirithell 于 2008-5-28 18:00 发表
assistance room ?  Where? open Time?

如果过我在EXAM中牺牲了，您能不能证明我是个好学生？

或者为我做点别的事情， 不我救回来？

我已经做到16题了，真难~~~~~需要非常非常细心~~~~

眼睛大都花了 ...

那个formula其实coursebook里面有。

不好意思，我还没有听说过stage 1统计可以商量分数的。

不用怕，好好学肯定能过，毕竟是一门每学期200 A+的课程。

江儿

物理问题 能不能也请教呢


The rate of heat flow through the down fabric clothing of a skier is measured ot be 230 Watts.Assume that the skier's skin T is 34'C and the mountain air T is 1'C. If,after a fall, the skier's clothing becomes saturated with water,determine how this heat flow would change if the Down clothing maintains the same thickness.
(k (D_C)=0.04)

帮帮忙了饿

z-score

原帖由 江儿 于 2008-5-30 09:23 发表
物理问题 能不能也请教呢


The rate of heat flow through the down fabric clothing of a skier is measured ot be 230 Watts.Assume that the skier's skin T is 34'C and the mountain air T is 1' ...

这个需要等一位会物理问题的朋友。

江儿

看来等不到了

doufu

plz help with the stats 125 assmt 5
Q1(B)the equilibrium distribution doesnot exist ,right?how to explain why not?
q4 could you give some hints for how to do (C)&(D)?
Q5
Q6
thans a lot.

wongchuntat905

no more stats assignment at last~~~so happy~~~

z-score

原帖由 doufu 于 2008-5-30 15:57 发表
plz help with the stats 125 assmt 5
Q1(B)the equilibrium distribution doesnot exist ,right?how to explain why not?
q4 could you give some hints for how to do (C)&(D)?
Q5
Q6
thans a lot.

不好意思，2004年的125没讲limiting distributions, 当时不是这位变态的Mark Holmes. 这几道问题需要dk7或其他高人的帮助。不好意思，现在125的最后一章超过阿童木的所能了。非常抱歉。

spirithell

The degrees of freedom for the Chi-square test will depend on the sample size.

z这句话对不对？为什么不对？

辛苦了，谢谢。

spirithell

Chapter 11, For simple linear model, df = n - 2

这个对吗？ QUIZ 4 说是对的，啊啊啊~~为什么？

z-score

原帖由 spirithell 于 2008-6-1 10:44 发表
The degrees of freedom for the Chi-square test will depend on the sample size.

z这句话对不对？为什么不对？

辛苦了，谢谢。

The answer is no, because the degrees of freedom for the Chi-square test will never depend on the sample size.

The degrees of freedom for Chi-square test is the number of rows minus one times the number of columns minus one.

z-score

原帖由 spirithell 于 2008-6-1 10:51 发表
Chapter 11, For simple linear model, df = n - 2

这个对吗？ QUIZ 4 说是对的，啊啊啊~~为什么？

That's correct because you lose one degree of freedom every time you estimate an unknown parameter. In simple linear regression, we estimate two unknown parameters, the slope coefficient and the intercept, therefore df = n -2.

江儿

For the asymmetric simple random walk with right-step probability p,find a
formula for p(n)/0m.

z-score

重要通知:

阿童木到这周末都不允许上skykiwi了。家庭问题，请多原谅。

江儿

For the asymmetric simple random walk with right-step probability p,find a
formula for p(n)/0m.

阿童木 帮帮我这个题啊

~Kurosagi~

問一下  要怎么複習stats會比較好???

~玫瑰无心~

原帖由 ~Kurosagi~ 于 2008-6-4 00:51 发表
問一下  要怎么複習stats會比較好???

从现在到exam的时候，不停的去做past exam.

寒冰

atm: 能不能放点341的past exam阿~~

dk7

也许今次太迟了，但下次的话可以PM给我啦... ; )

~玫瑰无心~

原帖由 寒冰 于 2008-6-4 13:20 发表
atm: 能不能放点341的past exam阿~~

I don't think he has any.

~玫瑰无心~

原帖由 dk7 于 2008-6-4 21:30 发表
也许今次太迟了，但下次的话可以PM给我啦... ; )

Yeah I agree, he should PM you.

spirithell

4000 BC Period                                        150 AD Period
Normal with mean = 131.4               Normal with mean = 136.2
and standard deviation = 5.1            and standard deviation = 5.3
x pr(X <= x) x                                     pr(X <= x)
123.011      0.050                                    127.48          0.050
124.864      0.100                                    129.41          0.100
130.759      0.450                                    131.40          0.183
131.400      0.500                                    135.53          0.450
136.200      0.827                                    136.20          0.500
What proportion of skulls from the 150 AD period have a breadth greater than
μBC, the mean breadth of the skulls from the 4000 BC period?

这个怎么做？ 谢谢~~~~~

z-score

原帖由 spirithell 于 2008-6-5 19:41 发表
4000 BC Period                                        150 AD Period
Normal with mean = 131.4               Normal with mean = 136.2
and standard deviation = 5.1            and standard deviatio ...

μBC = 131.4, probablity 150AD less than 131.4 is 0.183. 1 - 0.183 will be the probability of greater than the mean.

Vy2

hey atm.. can i pls ask a little question??
i don't quite understand how the 14/50 rule works..
in my course book it said its a guide to see if we should use t-distribution
then.. how does it work? how do i know whether to use t-distribution by using the 14/50 rule?
hope i made my question clear..
cheers =]

z-score

原帖由 Vy2 于 2008-6-8 20:51 发表
hey atm.. can i pls ask a little question??
i don't quite understand how the 14/50 rule works..
in my course book it said its a guide to see if we should use t-distribution
then.. how does it  ...

Hi Vy2, the 14/50 rule is quite recent in the stats course book. What it's trying to say is that if the sample size is smaller than 14, we will have almost always symmetric data. When the sample size is greater than 50, we can have severely skewed data. Hope that helps.