MATH 251, Probability and Statistics I, Fall 2001, Day 3

Final version
Trouble accessing Aurora?  Answer from Prof. Larson, Network guru:
Dear Sally, What you're describing sounds pretty clearly to be a problem with
the DNS configuration of the particular computers that aren't reaching Aurora.
It's likely that those computers also can't reach OPAC, Calendar, or any other
internal server, either--that is, not by name; they could reach them by IP.

The solution is to let Frank flacomb@wells.edu   know the exact names and locations of any
computers  having this problem, and he can reset their DNS so that Aurora and
the other internal servers are accessible to them by name.  Ken
Meanwhile I will leave a copy of the daily webpage in a blue folder outside my door.

Additions to text:
Timeplots: watch out for extrapolation: predicting beyond the range of the data.
Summary measures for center and spread.
    Mean is the center of gravity (balance point) of the data.
    Median is the value with half above and half below
    text website http://www.whfreeman.com/ips, scroll down to Select a Category,
        choose "Statistical Applets", Mean &Median. Convince yourself of the above.
        You can use it to help answer problem A below also.
    Mean collects all the "stuff" and tells what  each individual's equal share is.
        You can go from the mean to the (aggregate) total, if you know n, the number of observations.
Quartiles: The method given here is the quick-and-dirty method proposed by Tukey, who called them "Hinges".
    Other percentiles:  More exact methods exist, but there is not universal acceptance of any.
    The practical differences are small.  Moore &McCabe give a quick and dirty method at the end of example 1.15, p. 45.
Resistance: an important concept!
Boxplots   The outlier rule p. 47 is good to know about but don't bother to memorize it.  If you're doing a boxplot by hand just use your judgment about what's a suspected outlier.
NEXT CLASS: Standard deviation and variance:  I'll expect you to memorize the formula, and to be able to calculate this by hand for up to 7 numbers.


Unless otherwise noted, all assignments are in Moore & McCabe, Intro to the Practice of Statistics, 3rd ed. ("IPS")
Italics are notes to myself--which problem is it?

Day 3 (Wed. Sept 5) Assigned:
   (Re) Read:  1.2 thru p. 55 .Read for next class 55-58 ( linear transformations)We'll also start 1.3, Normal distributions.
Hand in: 
1.42 (elections, Q)
1.63 (dog sodium, box)
1.64  (SAT, boxes)
1.50 (0's effect)
Read 1.68 (guinea pigs, trimmed mean, cf. 1.27) 
      Make a boxplot of the data, with or without outliers (you choose).
       We'll do trimmed means with SPSS, next week.
1.43 (SSHA M/F,IQRoutlier) (Use xbars from back of book.)
Will assign next class:
1.54 (Do xbar and s by hand.  Then put them in SPSS & do them.)		 Read, discuss 
1.47(wealth)
1.49 &1.51(salary)
A.  If a distribution is skewed right,
the mean will be on the /right?/left?/ of the median.		 Optional

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