242 Chapter 10 test
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See comments below!
posted
at 11:10 PM
From N V Fitton, ideas to share with my students at Northern Virginia Community College, Alexandria campus.
I teach mathematics and computer science.
2 Comments:
A question is asked about #2:
Logarithmic regression y = a + b ln x, when predicting the market share for years 17 (2008), 19 (2010), and 29 (2020), is it possible to have in all three the same value = 20.5?
Answer:
I don't think that they should all come out the same! Log grows
slowly but surely. Maybe in way-out years we'd see "no change" at
this precision (one place after the decimal point), but I'm not
getting the same values that you do.
Also, note that 1990 maps to 1, 1991 to 2, ..., 2005 to 16, ..., 2008 to 19, ... 2020 to 21.
Additional comment on log: we start our table at 1 rather than 0 because logs of values between 0 and 1 are negative. Log 0 is not defined.
5:00 PM
> I just noticed that I went from 16 (2005) to 17 (2008)! I am now correcting
> the values.
>
There are several ways of seeing the right values. Two are:
use TABLE function (may require TBLESET first)
set WINDOW to have some space on right, then TRACE
5:23 PM
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