2008 First Semester STATS课程官方问答贴

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原帖由 A00118 于 2008-3-20 14:14 发表
e)   IP(W∪P｜R)是不是等于 IP(W｜R)+IP(P｜R)-IP(W∩P｜R)

请lsd稍等，我正在写反藏独的文章，马上就好。

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Wow, thank you 303B25, you saved me a lot of work.

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原帖由 ^曼陀罗^ 于 2008-3-20 21:48 发表
Question 4

only 25 students were accepted into the law programme, of which 20 were female.
应该是IP(F｜L∩A)=20/25  还是 IP(F∩L｜A)=20/25

完整的题目我已经发到[email=z-%3Ca%20href=]score1.96@hotmail.com[/email]">z-score1.96@hotmail.com了
还 ...

你好啊Datura, 今年谁哪位老师教125啊？

我看了一遍题目，我觉得events只有F(F`)和A(A`), 好像没有L, 我不太清楚你的L是什么意思。

IP(F|A) = 55/115 如果想算出IP(A|F), 我们需要用Bayes Theorem颠倒A和F的顺序。

我认为women bias就是看IP(A|F)和IP(A`|F)等于不等于。

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原帖由 ^曼陀罗^ 于 2008-3-21 10:24 发表
我晕了...阿童木....我问得是第四题了啦....
哈哈...第三题是第四题的前半部分...- -!L=student applied to the law program..
恩..我第三题就是那么算得...只是part b不知道怎么解释...
那是 ...

哦，不好意思。恩，明白你的问题了，不清楚怎样解释对吧？如果admission policies are fair, then IP(A|F&L)=IP(A|F&L`), IP(A|F`&L)=IP(A|F`&L`). 你把这些probability statements的意思写出来就能看出怎样解释那道问题了。

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原帖由 雨轩听风 于 2008-3-20 22:54 发表
for stats125 A1 Q2 d)
i) 52P3?
ii) I don't understand what mean by P(x). how to solve it?
iii) P(A∩B)=1/4?
then...P(A∪B)=P(A)+P(B)-P(A∩B)? I got negative probability...T_T......Is there an ...

我先让303B25和你对一下答案，如果还有不清楚的，我会继续解答。

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原帖由 liner 于 2008-3-21 10:42 发表
楼主··我也有这个问题...那些PAPER都下载不了```

哦，真的啊？那我把限权都撤了吧。主要是我开始不想让非skykiwi会员下载。

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原帖由 liner 于 2008-3-21 10:42 发表
楼主··我也有这个问题...那些PAPER都下载不了```

现在可以下载了吗？

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原帖由 Waiting... 于 2008-3-21 14:39 发表
你好！！为什么STATS10x的 ASSI 1 的第2和第3题好像和你给的答案不太相符~~

你是说我的worked examples吗？那个不是参考答案，只是我怎样去回答assignment类型的问题。因为很多朋友说不清楚应该怎样那英文回答问题，所以我上载了这样的一个文件。

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原帖由 ^曼陀罗^ 于 2008-3-21 10:51 发表
恩恩..好的..我试下..还有...

only 25 students were accepted into the law programme, of which 20 were female.
应该是IP(F｜L∩A)=20/25  还是 IP(F∩L｜A)=20/25

应该是IP(F｜L∩A)=20/25不是IP(F∩L｜A)=20/25，因为IP(F∩L｜A)=20/25是of those who applied, the probability of them being both female and law applicants.

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原帖由 ^曼陀罗^ 于 2008-3-21 10:53 发表
呀...303B25也有读125吗?我还以为很少人一起读两个呢...哈哈......
看了他/她之前的回复....是你的好帮手呀....
加油加油...

恩，我很感谢303B25给我的帮助。这个帖子比我以前想象的还要好，不光有我提供解答，大家还可以互相讨论。

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原帖由 ^曼陀罗^ 于 2008-3-21 22:18 发表
我也觉得是IP(F｜L∩A)=20/25...
但是这样的话....
题目要我们解的IP(A｜F∩L)怎么求出来..

可以用IP(A∩F∩L)/IP(F∩L)

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原帖由 liner 于 2008-3-22 17:22 发表
Stats 108

question 2

e) Is the Survey subject to sampling errors? briefly justify your answer
这个survey有sampling errors对吧...可是不会justify诶···

When you take a sample, there will be sampling error. If there isn't error, we will be doing mathematics instead of statistics.

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原帖由 阴雨天 于 2008-3-22 17:00 发表

希望能给出blocking的详细解释... 非常感谢!!!

假设一个experiment有100个人，你想把他们分为喝酒和不喝酒两个组。但是因为男女对酒的反应有可能不一样，你想尽量把每组分为男一半女一半。所以blocking就是先把这100个人分为男和女两个组，然后再分喝酒和不喝酒两个组，这样一共会有4个组。

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原帖由 阴雨天 于 2008-3-25 15:48 发表
101的asgm 5e 题目具体要求我们做什么? 请LZ告诉下~ 谢谢! 有点没看懂.... 5e跟你上传的PDF文件里的5e是一样的.

恩，第五题其实每年都是一样的。你们可以参考我上载的past assignment answers. Question 5e 就是让你画出来那个表格。

[ 本帖最后由 z-score 于 2008-3-25 17:03 编辑 ]

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原帖由 kirstens 于 2008-3-25 16:50 发表
yea, it's a little tricky. for these kind of questions, if you get confused, a venn-diagram (I must spell that wrong ,but never mind, you know what i mean) is very helpful.
125 is an interes ...

Thank you kirstens for your help, I opened this post for the same reason. I hope we can both keep our stats sharp.

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原帖由 A00118 于 2008-3-25 16:59 发表
i am asking stats125 Q5..not stats101....:(

Sorry, 现在马上给你看。

看了直后：

我对这道题不缺定，但是我想if you integrate a probability function over the entire domain, you should get 1.

希望哪位probability高手指点我们一下。

[ 本帖最后由 z-score 于 2008-3-25 17:11 编辑 ]

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原帖由 没蚊香的黑夜 于 2008-3-26 00:54 发表
STATS 108 THANKS
1. Which one of the following statements is false?

If blocking is used in the design of an experiment, then there is nothing to be gained from using randomisation in that d ...

1. Which one of the following statements is false?
If blocking is used in the design of an experiment, then there is nothing to be gained from using randomisation in that design.
Blocking and randomisation concern different aspects of experimental design. Having either blocking or randomisation doesn't mean you can't have the other.

2. In a web survey of approximately 2000 Stage 1 Statistics students, 915 responded.
The students were asked for their birth date and how long they hadlived in New Zealand. From this information, values can be found forthe variable Percentage of life lived in New Zealand.
Which one of the following statements is not a potential problem when analysing the responses from the survey?
Percentage of life lived in New Zealand was not one of the questions the students answered. This is not a potential problem because the question said "values can be found forthe variable Percentage of life lived in New Zealand."

3. Which one of the following modifications to Table 1 would not improve the table for presentation purposes?
Add a column of row averages. Finding the average of visitor arrival and average spending doesn't make sense. Visitor arrival is measured in person and amount spent is measured in $.

[ 本帖最后由 z-score 于 2008-3-26 07:59 编辑 ]

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原帖由 303B25 于 2008-3-26 11:15 发表
ATM

I'm trying to type out the assignment right now but I don't know how to type the complement, can you show me how to type a line on top of stuff please.

Hi 303B25, yep sure thing. Now if you are typing your assignment up in word, you would first need to click insert in the menu bar then click object, scroll down till you find Microsoft Equation 3.0.

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原帖由 303B25 于 2008-3-26 10:36 发表
5(a)

(i) make sure the probability is never negative
(ii) make sure the sum of it =1
(iii)probability of it equal to the integration of the function

not exactly sure with this one, try in ...

Wow, you are so good, I'm so glad I'm not on my own in this post.

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原帖由 303B25 于 2008-3-26 13:38 发表
I use openoffice, that's alright, I'll just write it on, easier.

I use open office on my laptop as well. I tried installing Office 2007 but don't know why it doesn't work on my vista

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原帖由 当时的理想 于 2008-3-26 19:15 发表
HI。。。 STAT 108 的第一个ASSIG。。。 的最后面2个小题。。写小评价那图的。。。请LZ给点小意见。。。。

WORD LENGTH 和WORD NUMBER。。 有些NUMBER 小。。但LENGTH挺大的。。 不知道怎么评价。。

还有 ...

你好，我可以帮你comment, 你能把你的图片贴上来吗？因为每个人的数据都不一样，comment出来的结论也不一样。这个plot的comment主要是看word length和number of words的relationship. For example, is there an increasing relationship or decreasing or no relationship? How is the scatter?

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原帖由 dk7 于 2008-3-26 18:33 发表
PM me would be good if you need help.  I could see myself being more active in the next half of the year...

Thank you dk7, I will do that, hope I don't bother you too much. I'll use this post as a good learning exercise for me to help people with stats. Hope you don't feel I'm bugging you too much.

[ 本帖最后由 z-score 于 2008-3-26 21:21 编辑 ]

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原帖由 没蚊香的黑夜 于 2008-3-26 22:08 发表
The sample mean,  , and sample standard deviation, s, of 15, 65, 64, 65, 15, 15 are:

   = 39.15, s = 24.33  
  = 39.15, s = 27.39  
  = 39.83, s = 27.21  
  =29, s = 28.58  
  =39.83, s =  ...

请问你用的那款计算器？Casio fx-82MS, fx-9750G PLUS还是其它品牌？

计算108的standard deviation不是Year 13的population standard deviation, 是sample standard deviation, 就是shift 3, 不是shift 2, 是那个sigma n-1符号。

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原帖由 没蚊香的黑夜 于 2008-3-26 22:14 发表
我的计算过程是：
（15+65+64+65+15+15）/6=39.83
[（15-39.83）^2+(65-39.83)^2+(64-39.83)^2+(65-39.83)^2+(15-39.83)^2+(15-39.83)^2]/6 然后开方=24.839xx

那里错误？

应该是除以5不是除以6,你算得是population standard deviation, 这个并不是s, 是sigma, 应该是除以n - 1, 6 - 1 = 5.

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我现在马上睡觉了，我能明天早上用你上面写的数据演示给你怎样用Casio fx-82MS计算standard deviation吗？

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原帖由 SnowDrop 于 2008-3-27 01:10 发表
辛苦z-score了，我试试计算器的问题好了，麻烦z-score帮我对对啊！～～


1：把计算器调到stat mode，就是按“mode/clr”键，如果看到“stat”的字样在显示屏上出现，就按“＝”

2：清除计算器的memory， ...

太感谢SnowDrop了，你做的肯定没错。没有蚊子的夜可以按照SnowDrop写的去计算。

原帖由 弥漫记忆 于 2008-3-27 02:55 发表
太谢谢LZ了，第一次写ASSIGNMENT，完全迷茫中
看完上边的，帮助很大

太好了。

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SnowDrop, 给你的dataset.

oooOOO我们都是阿童木。

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给好了，哦耶，我们都是阿童木。

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原帖由 SnowDrop 于 2008-3-28 23:20 发表
hope it helps~~~~~~

to z-score: can you access cecil for any papers？

是的。

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原帖由 clement001 于 2008-3-29 19:49 发表
可否解釋一下,box plot 如何看unimodal,bimodal

你好，boxplot不能看出来data是否unimodal或bimodal. 要看stem & leaf plot.