2008 First Semester STATS课程官方问答贴

luvwei

还吃chips呢

拿来给我吃点呢！！haha

你们两个第一题不太一样哦

我也觉得应该是0。25吧！

还有还有 。
第3题的d
怎么第三个statement我的pr。大于1了阿？？

这样是不是错的很严重？？

chips会胖的。少吃点。

z-score

原帖由 luvwei 于 2008-4-7 13:22 发表
还吃chips呢

拿来给我吃点呢！！haha

你们两个第一题不太一样哦

我也觉得应该是0。25吧！

还有还有 。
第3题的d
怎么第三个statement我的pr。大于1了阿？？

这样是不是错的很严重？？

chip ...

哦, 对对, 你不说我还没注意到, 第一题是0.25因为他问的是both red card and heart.

我来看看Question 3 statement 3.

嗯, 明天绝对不吃chips了.

luvwei

ooppsss 不是3

是2，4

写错了写错了

改天请你吃chips赔罪阿

哈哈

z-score

原帖由 luvwei 于 2008-4-7 13:22 发表
还吃chips呢

拿来给我吃点呢！！haha

你们两个第一题不太一样哦

我也觉得应该是0。25吧！

还有还有 。
第3题的d
怎么第三个statement我的pr。大于1了阿？？

这样是不是错的很严重？？

chip ...

ACT ~ Normal(21, 4.7)

SAT ~ Normal(500, 100)

Statement 1 - FALSE

21 - 2 * 4.7 = 11.6
21 + 2 * 4.7 = 30.4

因为95%的学生已经在11.6和30.4的中间了, 那么在11和30中间的学生会比95%更多, 而不是更少.

Statement 2 - TRUE

IP(ACT > 28) = IP(Z > (28-21)/4.7) = 1.489362

IP(SAT < 300) = IP(SAT < (300 - 500)/100) = -2

luvwei你说的是不是z-scores > 1? ATM大于1 is OK.

z-score

原帖由 luvwei 于 2008-4-7 13:40 发表
ooppsss 不是3

是2，4

写错了写错了

改天请你吃chips赔罪阿

哈哈

Statement 4 - TRUE

IP(ACT = 25) = IP(Z = (25 - 21)/4.7) = 0.8511 (4 d.p.)

IP(SAT = 610) = IP(Z = (610 - 500)/100) = 1.1 (4 d.p.)

是这道吧?

oooOOO 阿童木超喜欢吃chips

luvwei

所以z－score大于一是没所谓的是不是阿？？

你好厉害！！

哈哈！！

在学校吗？在座什么呢？

还在吃chips？

spirithell

is it all ? whatever I just try to remember everything  and no matter what they are.

nearly forgot ,thx~~~~~~

[ 本帖最后由 spirithell 于 2008-4-7 15:11 编辑 ]

z-score

原帖由 luvwei 于 2008-4-7 15:03 发表
所以z－score大于一是没所谓的是不是阿？？

你好厉害！！

哈哈！！

在学校吗？在座什么呢？

还在吃chips？

嗯, 是的, z-score的range是IR, all real numbers.

我在Epsom Campus这边上班呢.

Chips吃完了. oooOOO

z-score

原帖由 spirithell 于 2008-4-7 15:08 发表
is it all ? whatever I just try to remember everything  and no matter what they are.

nearly forgot ,thx~~~~~~

你看10x的coursebook里面关于Chapter 7的theory就两页. 需要答对考试里的两道Chapter 7选择题, 我刚才说的那些基本足够了. 知道太多容易搞混, 我知道我这样不鼓励学习和理解, 但是当你学完Chapter 8 - 10的时候, Chapter 7突然会变得简单了.

apric0tnz

我给你发邮件了，帮我看看吧~~~~

luvwei

原帖由 <i>z-score</i> 于 2008-4-7 14:16 发表 <a href="http://www.skykiwi.com/bbs/redirect.php?goto=findpost&pid=14502349&ptid=794272" target="_blank"><img src="http://www.skykiwi.com/bbs/images/common/back.gif" border="0" onload="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onmouseover="if(this.width>screen.width*0.7) {this.resized=true; this.width=screen.width*0.7; this.style.cursor='hand'; this.alt='Click here to open new window\nCTRL+Mouse wheel to zoom in/out';}" onclick="if(!this.resized) {return true;} else {window.open(this.src);}" onmousewheel="return imgzoom(this);" alt="" /></a><br />

<br />

<br />
你看10x的coursebook里面关于Chapter 7的theory就两页. 需要答对考试里的两道Chapter 7选择题, 我刚才说的那些基本足够了. 知道太多容易搞混, 我知道我这样不鼓励学习和理解, 但是当你学完Chapter 8 - 10的 ...

<br />


所以那个 mu是小sample mean from the whole population？？

z-score

原帖由 apric0tnz 于 2008-4-7 14:39 发表
我给你发邮件了，帮我看看吧~~~~

哪个email? [email protected]?

我好像还没收到.

apric0tnz

hotmail的~~~~~~~~~~~~

z-score

原帖由 luvwei 于 2008-4-7 14:41 发表



所以那个 mu是小sample mean from the whole population？？

给你一个很宏观的表格

Population              Sample                              Sampling Distribution
mu                             x bar                                    X bar
sigma                            s                                 not taught in 10x

z-score

原帖由 apric0tnz 于 2008-4-7 14:49 发表
hotmail的~~~~~~~~~~~~

我换email了, [email protected]

以前的那个被glasszon黑客掉了.

apric0tnz

收到没？~~~~~~~~~~

z-score

没收到, 发给我[email protected]?

apric0tnz

收到否？

加热的咖啡

原帖由 z-score 于 2008-4-7 12:24 发表


哦, 对对, 你不说我还没注意到, 第一题是0.25因为他问的是both red card and heart.

我来看看Question 3 statement 3.

嗯, 明天绝对不吃chips了.

阿童木,第一题他不是问both red card and heart吧? 他说 What proportion of students would answer the question: “Is your card a heart?”. 那Hearts and diamonds are red cards那也就是说只要你拿到red card你就会被问Is your card a heart 那不是50%的学生吗? 如果不对还请解释啊~~~~~~感谢前辈~~~~~~~~~~

z-score

原帖由 apric0tnz 于 2008-4-7 14:49 发表
hotmail的~~~~~~~~~~~~

收到了，家里没有Word, 明天早上帮你看没问题吧？

z-score

原帖由 加热的咖啡 于 2008-4-7 19:45 发表


阿童木,第一题他不是问both red card and heart吧? 他说 What proportion of students would answer the question: “Is your card a heart?”. 那Hearts and diamonds are red cards那也就是说只要你拿到r ...

What proportion of students would answer the question: “Is your card a heart?”

嗯, 你说得对, 我把题目理解错了. 应该是0.5.

z-score

原帖由 303B25 于 2008-4-8 10:52 发表
Help, question 4 (a) (b) what do they mean by in terms of the distribution of X and its parameters. I'm just getting so confused, should H0 be p = 1/2 or H0: X = 14??

Thank you ATM

Hi 303B25, just folding some envelopes atm for work, will get back to you asap.

apric0tnz

原帖由 z-score 于 2008-4-7 22:06 发表


收到了，家里没有Word, 明天早上帮你看没问题吧？

好的好的，周五前告诉我都可以~~~~~~~

z-score

原帖由 303B25 于 2008-4-8 10:52 发表
Help, question 4 (a) (b) what do they mean by in terms of thedistribution of X and its parameters. I'm just getting so confused,should H0 be p = 1/2 or H0: X = 14??

Thank you ATM

原帖由 BlackDatura 于 2008-4-8 12:46 发表
stats 210 a2 q2
b. IP(T1 | 4H1T) = IP(T1 & 4H1T) / IP(4H1T) = (1-p)*p^4 / (5C1 * p^4 * (1-p)^4) = 0.2

这是怎么得出来的啊?


另外 q4的a 应该怎么写

4. The Relative Age Effect theory says people born in the first half of the year have a greater chance of
being selected into top sport teams. We wish to investigate whether or not this is the case, using the
Auckland Blues rugby squad as our data. Let X be the number of members in a 28 member Auckland
Blues rugby squad with birth months in the first half of the year. In 2003, x = 15.

(a) Under the assumption that there is no relative age effect in the Blues squad selection process,
state the distribution of X, the number of members with birth months in the first half of the
year.

Ok, here is what I think.

X ~ Binomial (n = 28, p = 0.5)

I chose Binomial because we have only two outcomes, being selected into the team or not. The probability is 0.5 because we hypothesis that there is no relative age effect. The number of outcomes is 28 because we have 28 players in the team.

[ 本帖最后由 z-score 于 2008-4-8 13:31 编辑 ]

z-score

(b) We wish to test the hypothesis that there is a relative age effect in the Blues squad selection
process. Formulate the null and alternative hypotheses in terms of the distribution of X and its
parameters. Specify the full distribution of X and use a two-sided alternative hypothesis.

H0: p = 0.5

VS

H1: p != 0.5

z-score

原帖由 BlackDatura 于 2008-4-8 12:46 发表
stats 210 a2 q2
b. IP(T1 | 4H1T) = IP(T1 & 4H1T) / IP(4H1T) = (1-p)*p^4 / (5C1 * p^4 * (1-p)^4) = 0.2

这是怎么得出来的啊?


另外 q4的a 应该怎么写

这个算的方法是按照conditional probability formulaIP(T1 & 4H1T) / IP(4H1T)计算出来的。

IP(T1 & 4H1T)代表tail on the first, then followed by 4 heads. 他的probability会是(1 - p)*p^4.

IP(4H1T)代表1 tail and 4 heads in any order. 每一次1 tail and 4 heads的probability是(1 - p)*p^4, 而且我们有5种排列组合，5C1.

apricotnz

原帖由 z-score 于 2008-4-8 13:27 发表




4. The Relative Age Effect theory says people born in the first half of the year have a greater chance of
being selected into top sport teams. We wish to investigate whether or not this  ...

I asked the teacher today, there is no need to say the reasoning for your distribution. So just X~Binomial (28,0.5)  is enough.

apricotnz

原帖由 z-score 于 2008-4-8 13:34 发表


而且我们有5种排列组合，5C1.

why 5 choose 1?? why order doesn'r matter here??


p.s. when u gonna answer my 341