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Lack of Freq Calc (fwd)
Posted:
Sep 15, 1996 10:36 AM


 Forwarded message from AlCoons@aol.com 
I noticed in Workshop Stats that the data files on disk have every data item entered separately even when the data is given as tallies in the book (for example in Activity 310 (d,e)). It is clear from previous emails that dealing with frequency data is difficult with Minitab. However, it is very easy to do on the TI83 (stat calcs and plots all will handle frequencies).
 End of forwarded message from AlCoons@aol.com 
Each variable is a column and each row is a case is standard database practice, not peculiar to Minitab or even statistical software. And there is a reason for this. As soon as you have two variables
1 4 3 4 3 2 it is clear that you do NOT want to store this as
1 1 2 1 3 2 4 2
as that completely destroys the information on which x goes with which y. It's the same problem as sorting your data one variable at a time  it completely scrambles your database.
If you START with data like this, you can still enter it into Minitab just as easily as the TI83 (check "set with patterned data" in the index) but it will STORE it in standard database fromat. (Of course it cannot restore the lost information.)
Because it handles variables in a consistent way, if I have 100 variables in Minitab, I can
describe c1c100
and get (correct) summary statistics on every one. If I could store 100 variables in the TI83, I'd have to go through them column by column to determine which columns are actual data and which are frequencies. If I don't, the calculator will STILL compute answers, but they will be wrong for all data stored in the "onevariable=2columns" format. I think this is a "feature" of the TI83 that would be a nightmare if it were powerful enough to do real data analysis. Fortunately, it is not.
_   Robert W. Hayden   Department of Mathematics /  Plymouth State College   Plymouth, New Hampshire 03264 USA  *  Rural Route 1, Box 10 /  Ashland, NH 032179702  ) (603) 9689914 (home) L_____/ hayden@oz.plymouth.edu fax (603) 5352943 (work)



