Math 151 , Day 12, Wed., Sept.19, 2007 Hit Reload...After class.

Hand In Friday "Day 11" Normal HW repaired + "Day 12": "Backward x problems"--Listed at bottom of Day 11 HW. Chapter 4 intro: : p. 92, 4.1 explanatory/response or just association     4.2 expl/ resp in an experiment (coral)     4.3 beer and blood alcohol, other variables \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ Postpone all the rest! p. 108, 4.24 date heights Make the scatterplot by hand.  Answer these questions instead of the ones given:  Describe the relationship--form, direction, strength,  (with only 6 points there's not enough data  to talk about outliers).  Is there any female dating a male shorter than she is?(Keep a copy of the graph, to use in the next hw.) p. 107 4.23 reading ability - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -   Scatterplots using SPSS.  Scatterplot handout p.1-3, p.4 ---From now on, make all scatterplots on SPSS!  Don't forget to check Measure, and to add Labels. SPSS Scatterplot Handout:  Use the handout and govsal_vs_pay.sav  data file to use SPSS and answer questions 1-5 (page 3 of handout).  Keep the Handout questions separate from the rest of your HW; hand in all the Handout questions at once, only  when all 12 are finished! p. 96, 4.4 and 4.5 (SPSS) bird colonies(Save your file; you'll use it again for 4.10) p.96, 4.6 (SPSS) gas mileage p. 98 4.7 (SPSS) icicle growth. Data is in table 4.2. Be sure to write on your graph which group is slow water and fast. p. 109 4.25 a, c (not b) (SPSS) running records, M/F These are record breaking times, so a year without a number is one in which the best time was slower than the last record. (Keep a copy of the graph, to use in the next hw.)

Read, to discuss

Optional  Do now if you need the practice: Straight line graphing practice: A.  y = -10 + 3x, graph for 2<x<10. B.  y = 500 - 20x, graph for 0<x<10.

Exams still not finished.  Sorry!  Friday for certain!
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HW Questions?  Using z tables to go between raw values and proportions (percentiles)  See Day 11
  Optional Handout:  Using SPSS to compute new variables, find Normal table values

Handout:  Solutions p. 87, 3.46 surprising difference in tails
Correction in handout: 3rd line from bottom is .9881as in the following lines.
    p. 80-81 3.11 and 3.12 (locomotive adhesion, 2 dist's)   

"San Diego Reader"  --What proportion of pregnancies last 310 days or more?  z = (310-266)/16 = 44/16= 2.75.  Area above 2.75 = .0030.
        3 in a thousand pregnancies last that long.  Pretty rare.  Is "San Diego Reader" one of the 3-in-a-thousand, or is she lying?  (this is the kind of question we deal with in Significance Testing, part 3 of the course).Discussion

More on backward problems?  Going from area to x: Day 8
= = = = = = = = = = = = = = = = = = = =
Relationships: (BPS4e Ch.4, at first to p. 98)  
Two Related quantitative variables  (We used side by side stemplots, boxplots, histograms to relate a quantitative variable to a categorical variable)
    "Just Related" or "explanatory & response?"
(Scatterplots)
explanatory = independent = "x" = horizontal axis ( = "cause", sometimes but not always)= predictOR
  response =    dependent = "y" = vertical axis      = ("effect ") =predicteED

(Living histograms:  Height vs. weight, Height vs. gpa)

Got to here Wed.
Discussing Scatterplot
General Pattern                                      Deviations
Clusters?                                                      Outliers? (label if possible)
Form (linear, curved, ...?)
    Strength of relationship (how unfuzzy)  "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. (BPS Ch. 4&5)  pages.1-3  ,  page.4 
govsal_vs_pay.sav  is the file used for most of the handout.