Got these few emails:
My response:
Then this one:
My response:
My response:
Sudhir
Dear Prof/TA,
I could see two different Homework Part II for Session 7. One in page 11 of the handout that was given to us.
The other is in the slides in Addendum slides for session 7 called Homework Part II ( Optional )
My question is, which one is actually Homework Part II for session 7 and is it optional ? Sorry if I misunderstood instructions in the class.
Thanks
H
My response:
Yes, the slide deck contains the optional part. Feel free to ignore it.
There are two questions in session 7 Hw - one related to standard regressions (mobile usage example) and one related to multinomial logit in worksheet 'hw4 MNL'.
Hope that clarifies.
Then this one:
Professor,
I am unclear on Part-II of hw 7. We are asked on predicting the edulevel using the means and modes of the relevant model. So we have the “us” or the numerator part of the logit model, but not the “them” part.
To analyze the “them” part, we have 3 levels in rateplan, 3 levels in gender and familysize.
· Is taking family size as the mean vale for the denominator appropriate?
· If so, this will give a total of 9 combinations (or parts) for the denominator.
· We then look at the probability of education level 1 and 2 and whichever is more probable is our answer
Is this approach correct?
Sincerely,
R
My response:
Hi R,
Pls look at the addendum for session 7 in which is put up on LMS on the logit based prediction model.
There, given a set of X values X={10,9,1} for {sales, clientrating, coupon1}, we predicted the probability of instorepromo being 1,2 or 3.
Similalrly, once you have a set of Xs for {edu, famsize, rateplan, etc.}, use the SAME X profile in both the numerator and the denominator of the logit expression.
Hope that clarifies.
Another:
Hi Chandana, Can you let me know where the worksheets for the homework are? I’m unable to find them on LMS. Session 7 slide 29 says worksheet labeled ex2Session 7 slide 44 says worksheet name ‘hw 1 MNL’ I can’t find either. Thanks,RC
My response:
'ex2' is the standard regressions based homework - mobile usage one. 'hw4 MNL' is the logit based homework. It was wrongly written as 'hw1 MNL'. MNL is Multi Nomial Logit in the sheet name. I hope that clarifies.Shall putup more Q&A homework related as they happen in this thread. More recent on top.
Sudhir
For HW7 Part 1, we have to regress Usage on rateplan, gender, and rateplan*gender. For the composite variable: rateplan*gender, we will have 3 different variables (rateplan1*gender, rateplan2*gender, and rateplan3*gender) or just one!
ReplyDeleteProblem with using just one variable - rateplan*gender is that for a given respondent, only one of the rateplans is true (i.e. 1 (in metric scale) and other two are 0).
So if we do gender*max(rateplan1, rateplan2, rateplan3), then we just end up repeating the gender distribution.
Hi Anon,
ReplyDeleteYou have one usable gender dummy variable and 2 usable rateplan dummies. In total, you'll get 3 dummy variable columns if you interact rateplan and gender. However, again, one of these columns will be a linear combination of the other 2. So in all, there will only be 2 usable gender*rateplan dummy columns. Hope that helps.
Sudhir