Math 151 , Spring 2005, Day 10 Mon. Feb. 21 Hit reload...After Class

--Exam 1  Friday Feb 25, Day 12, in class, closed book.   Bring a simple calculator. I will give you copies of the Normal table.  If you will need extra time, make arrangements with me by Wednesday, please.
Covers through  Part I:through p.112.  You will need to read SPSS output, but not tell how to produce any. You will need to calculate "by hand" a standard deviation for four numbers. (As well as medians, quartiles, etc.)   Problems like HW + some true-false or multiple choice types.
 Sample exam was given out.
HW Day10 (Mon. Feb. 21): Bring questions for exam.!!
Reading ahead:  D&V Ch7 Scatterplots, first thru 117 (AS7-1&2), then Correlation, the rest. (AS7-3&4) You do not have to be able to calculate r by hand.  You should be able to guess roughly at an r for a swarm of data.

Nothing to Hand in Wed.(From D&V unless otherwise noted)Postpone all:
p. 130, 5,6 describing simple plots
 1,4 what relationship ALSO sketch an appropriate scatterplot for each.
  8 Derby (This is actually a timeplot)ALSO, how does the variability  change over the decades?
 9 Pottery For a, dotplot is ok instead of histo.  ALSO, is Batch # really Quantitative, or Ordinal?

SPSS Handout: Repeat the work of page 1, and do problems 1-5 on p. 3.  Keep this work and hand it all in when all problems have been assigned. 

HW in Activstats:  Go to Chapter 7, use the menu button with the House icon.  Scroll thru the problem list to find the ones given.  In each problem involving data, a button will allow you to launch SPSS and open the correct file.  Then save the file for yourself, do the analysis.
MRA-81-4 (SPSS) Metabolic Rates, M/F
MRA-83-8 (SPSS) Ed. Spending vs. Teacher Salaries
MRA-80-2 (SPSS)  Speed vs. Fuel Consumption (describe)
TRE-58-26 (SPSS)  Bear neck/weight  ALSO Make a plot with the M&F bears marked differently.  What if any sex differences do you see here?

MRA-95-13 (SPSS, and pencil) Corn plants.  This is a first introduction to the idea of predicting or estimating a "typical" y for a given x value.  Ch. 8 will do an important special case of that.
Read,
 to discuss
Optional 

 

Normal distribution, Homework? (Standard normal, day 8, 20&22, "real/raw" Day 9 )
Class was spent on Normal dist.  Start here Wed. after questions about exam
Relationships: (D&V Ch 7 thru p.117, AS7-1&2  )
    Did 2 categorical variables (2-way tables), quantitative vs. categorical (side-by-side boxplots, stemplots, histo's)
Relating 2 quantitative variables:  Scatterplots
   explanatory = predictor = independent = "x" = horizontal axis ( = "cause", only sometimes!)
                        response =    dependent   =  "y" =  vertical axis      = ("effect ")

(Living histograms:  Height vs. weight, Height vs. gpa)
Timeplot (p.43-4) is special case, "time" on x axis.

Discussing Scatterplot :
Unusual features?   Clusters (analyze each separately)?     Outliers? (label if possible; who?, why?)
For simple cloud, line, or curve:
Form (linear, curved, ...?)
    Strength of relationship (how un-scattered)  "Weak, moderate, strong"
Direction
    Positively associated:  y increases as x increases (generally).
    Negatively associated:  y decreases as x increases.

Mark subgroups differently to do comparisons. (Subgroups defined by categorical variable, like Sex, Region of country)
  Some scatterplot data:  educ-v-mortality.sav  ,   studatsp03.sav
Handout on SPSS Scatterplots etc. (D&V Ch. 7-10, AS 7,8,9)
govsal_vs_pay.sav  is the file used for most of the handout. (In SPSS for Class 05 folder)


Correlation (D&V Ch.7 pp118ff, AS7-3&4) -- a number measuring strength of linear relationship.
Website,  http://www.whfreeman.com/scc,
ClickNetscape toolbars to minimize them, if needed.
  Choose "Statistical Applets",  Correlation/Regression.  Play with data points, observing the Correlation Coefficient.
    Check in the "Show Mean X &Mean Y lines" box.  See how much is in each quadrant.

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