DSC 330 - Business Statistics

Statistics in Action 4

When is it?

The fourth for-credit "Statistics in Action" session will be held in class on Monday, week 10.

What you need to do

You should prepare for the session; it will be based on the situation outlined below. Before class, read the outline and get together in your group to discuss the problem. You should also use SPSS to analyze the data: you will need the FAST100 data file. Then, when you come to class you should be prepared to participate in a class-discussion, using what you've already discussed in your group. You can (and probably should) make notes on what you've discussed in your group before class. You should bring these notes to the class-discussion.

As in the last "Statistics in Action" session, there is something to turn in for this session by 4pm Sunday June 1. Send the instructor (by e-mail at ipardoe at lcbmail.uoregon.edu) the R2 and s values (accurate to 3 decimal places) for your group's "best model" (see below), together with sufficient information for the instructor to replicate your results, i.e. which predictors, interactions and/or transformations are in your best model. If you do not send anything to the instructor by the deadline your group will automatically receive zero credit for this SIA session. (The instructor will e-mail you to say your results have been received, so do not assume your e-mail went through successfully until you receive this confirmation e-mail.)

What will happen

Grading for the sessions will be on a zero/full credit basis. Each member of a group will receive full credit for that session if the group obtained a model almost as good as (or better than) the instructor's "best model" (i.e. R2 at least as high and s at least as low), or, if not, if at least one of the group makes some relevant remark in the ensuing discussion. If the group was unable to come up with a model as good (or did not provide enough information to replicate the results) and no-one in the group makes a useful contribution to the discussion, everyone in that group gets zero credit for that session. If a group fails to e-mail the instructor their model results on time they automatically receive zero, regardless of whether they contribute to the class discussion.

In class we'll discuss building a regression model for this dataset and also anything else that comes up that you think is relevant or interesting in the context of the problem. To keep the class-discussion orderly and the grading fair, you must raise your hand before saying something. The instructor will ignore anything you say unless you've raised your hand first and been asked to speak. The instructor will do his best to allow the first person to raise their hand the opportunity to speak each time. If you keep your hand up, you will be given the opportunity to speak once the current speaker has finished making their point.

When you make a relevant observation, suggest a useful approach to answering a question, or raise an interesting question not previously considered, the instructor will make a note of which group you are in, and keep a tally of which groups have participated and which have not. Remember, you only need come up with a model as good as the instructor's, or, failing that, make one relevant remark to get full credit for your group. The instructor will decide what is relevant and what is not, and his decision is final - no arguments.

The situation

You've been asked to develop a regression model for predicting company stock price. You have data on 100 stocks, and would like to build a regression model for predicting logY = natural logarithm of current stock price from 7 potential predictor variables:

Note that market is a qualitative (categorical) variable with three levels. Do not use this variable as a predictor; instead, you will need to use two dummy indicator variables based on this variable to model differing "market effects." For example, your two indicator variables could be D7 (= 1 for market 2, = 0 otherwise) and D8 (= 1 for market 3, = 0 otherwise), so that market 1 is the reference level. See SPSS Help #3 for how to create these indicator variables. This assignment is focused on model-building, not interpretation, but if you wanted to interpet models that include these indicator variables, you would plug-in D7 = 0 and D8 = 0 for market 1, or D7 = 1 and D8 = 0 for market 2, or D7 = 0 and D8 = 1 for market 3 (see pages 153-158 in Chapter 4 of the book for another example).

Build a suitable regression model. You may want to consider the following topics in doing so:


© 2007, Iain Pardoe, Lundquist College of Business, University of Oregon
Last updated November 14, 2007