2008 First Semester STATS课程官方问答贴

z-score

原帖由 yuyu 于 2008-5-13 12:28 发表
Fatal snake bites occur in Australia at an average rate of  "per yea"r. In a particular "3 month period",
2 fatal snake bites are observed. We wish to estimate .

 is lambda

that's why i ...

Yeah, 2 for every 3 months, your variable is also in terms of 3 months right? So it should be 2 right?

z-score

原帖由 luvwei 于 2008-5-13 12:13 发表
so i assume that
b) 1,2,4,5

c i) 1,2,4,5?
  ii)3?

d) 3? how do we knw we have learnd nothing??

b) Yes
c i) 1
  ii) 2 & 4
d) 3. Not statistically significant and can't tell about practical significance.

z-score

原帖由 303B25 于 2008-5-14 21:51 发表
hey ATM can you send a message to qian qian please, just tell her I read her message and I got exactly the same answer as her for all the questions.

Yep cool, I'll do that right now.

luvwei

108 Q4

box plot ..

do we make one for incr1 and incr2 on the same graph or seperate??

how cum my graph loooks so weird. for incr two , the max. point overlaped with upper quatile?

t-multiplier

原帖由 luvwei 于 2008-5-15 10:31 发表
108 Q4

box plot ..

do we make one for incr1 and incr2 on the same graph or seperate??

how cum my graph loooks so weird. for incr two , the max. point overlaped with upper quatile?

Sorry I don't currently have the assignment sheet, but from memory, isn't Q4 a paired t-test? If it is a paired t-test, then we are plotting the differences. Not a side by side dot plot.

spirithell

不好意思，又来了，每次都忘记说谢谢！

我就想问一下，chapter9,10重要吗？感觉老师就是在拖延时间。

不过还挺难的，就是把人弄晕那种，嘿嘿~~~~

dmx7

stats 125..
1. Let X~U[0,1], and A be the event that X<1/3
(a) Give the c.d.f of X
(b) Find P(X<=x|A)
(c) Find E[X|A]

3. Given a collection of independent random variables Ui ~ U[0,1], i= 1,2,.......
(a) how can you obtain a random variable X with c.d.f given by FX(x) = x/2 for x belongs to [0,2]?
(b) how can you obtain a collection of independent random variables Xi, each with c.d.f. given by F(x)=x/1+x, for x>=0?

6. Let U~U[0,1]. For x,y belongs [0,1], find P(X<=x, Y<=y) when
(a) X=Y=U
(b) X=U and Y=1-U

I hav no idea how to do these ... could u give me sum help plz...

z-score

原帖由 spirithell 于 2008-5-17 18:25 发表
不好意思，又来了，每次都忘记说谢谢！

我就想问一下，chapter9,10重要吗？感觉老师就是在拖延时间。

不过还挺难的，就是把人弄晕那种，嘿嘿~~~~

final exam的三分之一都是chapter 9 and 10.

z-score

原帖由 dmx7 于 2008-5-17 20:16 发表
stats 125..
1. Let X~U[0,1], and A be the event that X

1
a. You can integrate the pdf to get the cdf.
b. Use the conditional formula IP(A|B) = IP(A & B)/IP(B)
c. Use the conditional expectation formula, int(X*IP(X=x|A))

2.
a. I think it is 2* Ui.
b. Is the F(x) = x/(1+x)?

3.
I need to read up on some notes first.

z-score

早上起来等待Cecil login stats125, 现在连assignment都看不到.

z-score

原帖由 Nokia 于 2008-5-18 09:33 发表
Suppose N(t) is the number of sightings of a certain species of birds in the given location during observation time t. Let us assume tha N(t) forms time-homogeneous poisson process, so that expec ...

这个问题是哪张paper的?

z-score

原帖由 雨轩听风 于 2008-5-18 09:29 发表
ATM. 你能告诉我怎么做stats 125 assignment 4 question 2吗?
PDF的格式 我没有办法把题目复制上来

你用select tool可以copy, 现在Cecil上不去，我都看不到assignment.

z-score

原帖由 雨轩听风 于 2008-5-19 10:36 发表
http://tinypic.com/view.php?pic=295xrox&s=3
这个是题目..

Is this question a STATS125 question? It seems to be harder than usual.

For part a, integrate the exponential function.

part b, use integration and conditional probability formula.

part c, use the conditional expectation formula.

once you have part a to c, I think d and e should be ok.

spirithell

Stst101 A3  Q2
Difference Between Two Proportions, p1 – p2, what kind if situation is?

a lot of people said is situation(c), but i think its situation (A),  .........

form the forum , too many opinions, include Tutor Matt ,he confued us......  such a b  ...

z-score

原帖由 spirithell 于 2008-5-19 19:56 发表
Stst101 A3  Q2
Difference Between Two Proportions, p1 – p2, what kind if situation is?

a lot of people said is situation(c), but i think its situation (A),  .........

form the forum , too ...

situation C for sure, the sample sizes are the same, there is no way it is situation A. The first three words of the question says "A random sample", there is your answer.

江儿

阿童木在么。。。。。。
帮帮 stats125哦 这次A4好难啊

z-score

原帖由 江儿 于 2008-5-20 12:00 发表
阿童木在么。。。。。。
帮帮 stats125哦 这次A4好难啊

哪几个问题？

江儿

第一题的B
第4题的 为什么 P4 那一排的和是 0.1 应该是1 阿

江儿

第 5 第6题也不会

江儿

为什么不能打开第21页我呢晕菜了

江儿

第6题主要是为什么我的a和b 的答案都是xy呢？

z-score

原帖由 江儿 于 2008-5-20 12:38 发表
第一题的B
第4题的 为什么 P4 那一排的和是 0.1 应该是1 阿

Question 1 b, 用conditional probability formula.

Question 4 P4 那一排的应该是1,没错.

z-score

原帖由 江儿 于 2008-5-20 13:07 发表
第6题主要是为什么我的a和b 的答案都是xy呢？

有没有人做出来的,对一下.

z-score

原帖由 江儿 于 2008-5-20 12:40 发表
第 5 第6题也不会

第五题不会做, , course book里面有没有.

~Kurosagi~

10X 好晕阿作的

有没有人做了的“分享一下可以吗？？

谢谢