From: Daniel Manrique [dmanriqu@stat.cmu.edu]
Sent: Monday, January 21, 2008 9:14 PM
To: Brian Junker
Subject: Quiz1

Attachments: Grades303-1.csv

Hi Brian,

I'm attaching the grades for the Quiz.

**Common errors:
- A lot of people confuses variance with standard deviation (question 5.e)
- In question 3.f. almost half of people that answered the question 
constructed the interval using the standard deviation instead of the the 
standard error.
-(not an error, but might be useful to tell them): some people computed 
correctly the CI, but didn't realize that they had the standard error 
already computed! and used the formula "mean +-1.96*sd/sqrt(n)" instead 
of just "mean +-1.96*se"

**Other things:
In question 1b I haven't been strict and have tolerated some weird 
answers like a couple of "normal skewed" that *could* be reasonable.

**People we have to worry (some have good scores, but I think they have 
some serious problems)

*Mansour Neslawi (80): Completely lost in sumation notation and got 
wrong the expected value computation in 6c
*Chris Polanco (60): sumation notation (5a right, but didn't answer the 
rest) and half q6 missing.
*Megan Killeen(51): wrong definition of median(3b) scatterplot question 
(5) and summation notation (5a right but the rest wrong)
*Deok-hoi Koo (57): Almost all question 3 wrong or missing; same with 4 
and 5
*Young Ho Kim (61): Summation notation and binomial distribution.
*Justin Pincar(75) : question 1 with a lot of errors (and when didn't 
know the answer... filled with a joke...). Wrong definition of mode and 
median *but* the "hard" questions (4,5,6) right!
* Rusty sewell (69): sumation notation and binomial distribution

**Stats courses taken (N=22)
201 202 207 208 217 220 225 226 295 301 309 310 315 350 401 402 410 461 
462 795
 13   8   3   3   1   2  13   5   1   1   5   3   2   2   3   1   1   
2   1   1

I hope this gives you a clear pictures of what's going on.

Best,

Daniel