Summer School STATS108 & 208 官方问答贴(恭喜得到A+的同学们)

^曼陀罗^

太好了~~~~~~~~~~~~~~~~~~~~~

z-score

当时我也没有drop wrist.

我去看一下当年的model answers.

^曼陀罗^

因爲當時你也剛學20x嘛...想得沒有現在這麽遠....

z-score

恩，ms我没有drop wrist就得分了。最后的resid.plot的P-value也是significant的。没有问题。

z-score

对，没错，但是就没有print Assignment 5的model answers。天那，以前在stage 2就要做AVP和leverage residual plot.

^曼陀罗^

沒有drop掉wrist的話..我resid.plot的p-value是0.0572..

那不是大於0.05嗎?還算significant?

^曼陀罗^

那就是説我們現在讀20x和以前相比,還是很幸福的~哈哈

^曼陀罗^

還有,那個cook's distance..雖然有三個比較大的數值.但是那些也不算是unusual observation吧?

z-score

恩，不算。

z-score

没错，以前108还有binomial和poison distribution, distribution of sample proportions.

z-score

他每年的data都稍微变动一下，不过我是不要你drop wrist的。

^曼陀罗^

哈哈..那就不DROP WRIST了....啦啦啦..我去奮鬥ASSIGNMENT.....

謝謝你啊...有問題我繼續來問你..

z-score

阿童木马上就去马车会喝茶去了，有问题晚上见。

^曼陀罗^

我都希望順順利利完成作業...哈哈.....那樣就不需要一直問你啦....蠻不好意思地

你慢慢

z-score

哈哈，我希望semester 1能有更多人的人来问我。哦耶。

^曼陀罗^

Quest ion 2. [ 10 marks for Technical Notes and 8 marks for Executive Summary ]
The manager of a small retail chain has recorded data on sales, advertising and promotions. It
was of interest to determine how sales were affected by the amount spent on advertising and
the type of promotion that was used. The data are stored in the text file “sales”, which
contains the variables:
Sales the sales per week (in $000’s)
Advertising the amount spent on advertising (in $000’s)
Promotions the type of promotion used:
1 = 10% discount offered on all sales
2 = no promotion used
3 = competition with a major prize

这道题目，observations are not independent,对吗？

^曼陀罗^

是我粗心,沒有仔細看題目....
Q3的notes説道:"in the model building process, only retain explanatory variables that are significant at the 5% level."
wrist的p-value是0.0845....所以..- -!要drop的?
真不好意思阿..還麻煩你去找past assignment

z-score

原帖由 ^曼陀罗^ 于 2008-2-10 14:33 发表
是我粗心,沒有仔細看題目....
Q3的notes説道:"in the model building process, only retain explanatory variables that are significant at the 5% level."
wrist的p-value是0.0845... ...

恩，看来阿童木还是应该跟着感觉走。我总觉得wrist drop掉爽快。

好了没事了。

^曼陀罗^

不好意思嘛...我以后一定认真看完题目才问你的~呵呵~~~~

对了~你还没有答我136楼的问题~~~

麦秆

hey...108..assignment 3...question6 ( c )..5 should be B OR E and why??also...for question 7 f ( 3 )..can we say public holidays has the greatest underlying mean attendance by compare CI range( data)....for question 4...i did two sided but my friend ask for if she can do one sided...according to ' Does this mean that fewer ppl travel on Friday 13th'....thank u!!!!

z-score

你觉得不是independent? 为什么？

z-score

你能把整道题的description给我发出来吗？

z-score

原帖由 麦秆 于 2008-2-10 17:26 发表
hey...108..assignment 3...question6 ( c )..5 should be B OR E and why??also...for question 7 f ( 3 )..can we say public holidays has the greatest underlying mean attendance by compare CI range( d ...

Can you paste the question for question 6 c here? I can't remember what the question is. Yep we can for question 7.

z-score

Do a two-sided test, from memory I remember the question said something like is there a difference.

^曼陀罗^

Quest ion 2. [ 10 marks for Technical Notes and 8 marks for Executive Summary ]
The manager of a small retail chain has recorded data on sales, advertising and promotions. It
was of interest to determine how sales were affected by the amount spent on advertising and
the type of promotion that was used. The data are stored in the text file “sales”, which
contains the variables:
Sales the sales per week (in $000’s)
Advertising the amount spent on advertising (in $000’s)
Promotions the type of promotion used:
1 = 10% discount offered on all sales
2 = no promotion used
3 = competition with a major prize

這個就是整個題目....我..........覺得不是independent....是因爲.... 是一個人啊..而且都是它自己收集來的數據阿..又沒有説是random,又沒有説是experimental.難道我理解錯誤了... 我就是沒把握才問的...

z-score

没事，independence assumption is fine每个公司没有互相关系。

^曼陀罗^

這樣都算是independent呀 我還真沒想那麽多
我還以爲要出現那些比較專業的字眼才算...哈哈

麦秆

is there a difference between the proportion of arts students studying full time and the proportion of science students studying full time?


two sample t test on a difference between two proportions

or one sample t test on a proportion(whole students as a sample)

z-score

Two sample t-test as arts and science students come from independent samples.

Scofield

受益匪浅，顶了~~~