We'll start using SPSS Wednesday--have
class in the
computer lab that day. Everything by "hand" till then!
Needed for HW: Stemplot,
rounding when there are more than 2 decimal places? Handout says
truncate
(round
down), D&V text
says round to nearest. Tukey, the inventor, said
truncate;
throw away the trailing digits; I agree. This is supposed to be fast--rounding
to nearest slows it down. I encourage truncating but you can do
it
either way and be right. If you truncate, your stemplot may look
a little different from the text answers. (A stemplot
is
hard for a computer to do, but some packages do. For them, rounding to
nearest is easiest. SPSS truncates, which is hard for a computer.)
| Note: Many people missed
seeing that Ch 2 p.13, 4 Oscars,
5 Bears was part of Day 2 HW. I've asked
Fay to not count it late if it comes in Monday. Day 3: Hand in Monday (all from D&V text) (Postponed problems are repeated here.) Ch 3 p.28, TheBar/pie templates handout is helpful in creating the displays. 5 Death; 12 Teen Tech II 13 Auditing [I could disagree w/answer to b] Ch4 p 50 Creating: 12 bird species (10's as leaves, split 5 leaves per stem is good. Big outliers) 18 Marijuana (stem &leaf) p.104, #1a, banana price Make a stem and leaf and a dotplot. For the dotplot make a stack of each different number (e.g. a stack of 51's and a stack of 52's...) Which display do you like better? Describing: 5 Heart attack stays 9 Wineries: Make a) "under 60 acres". Book's answer to b is screwy, why? 14 Pop. growth More Ch4: #4 more shapes A. Use your circle data and make a back-to-back stemplot of Time (first column) for your two hands. Write a few sentences comparing the speed performance of your hands. |
Read, be able to discuss in class
Ch3 11 TeenTech I Ch4 Creating: 17 Acid rain Look at answer, note stems used Describing: 7 Cereal sugar 6 Emails (I think the answer book does a crummy job) 19 Hosp. stays Do a only. Read answer to c. Most mothers & babies go home in 2 days now. What W's are crucially omitted here?
|
Optional
|
Find someone you don't know (or who might
not remember you) and (re) introduce yourself.
Don't forget to initial the sign-in clipboard.
Monday: here in
classroom. Wednesday:
Come to Computer Lab, Mac 101. Bring text; disk or usb to save on
(containing your circle data if possible.)
Class
email list, Math151@wells.edu
Cluster in 3's, 4's or 5's.
Check for
Homework questions? Remaining #s on board.
Each group fill in summary sheet of
Circle colors/hand. Pool separate results. (Hand Summaries in)
Your questions
Pretests: Mixed, mostly ok:
Order of
op's-- Please Excuse My Dear Aunt Sally: Parentheses rule;
Exponents,
x, /, +, -.
Take it to math
clinic, anyone, ask for problems like the ones you missed.
Data:
Numbers
in context: Who (are the cases
&
how many =n),What (&units), When and Where, How,
Why?
Context for height, hair color,
shoe size, pulse rate: Any problems with the way I did it?
Variable (possible values), individuals
(cases)
recall
Categorical
(ordinal--has
natural order or &&nominal--just
names)
or Quantitative
(can add, average--measured on a ruler-type scale) Units?!
("calories"?)
OBJECTIVE (from syllabus): To learn many of the ways in which data can inform us about the world, focusing on
Distribution of one variable: Area represents proportion. ="Area principle"
Categorical:
(Relative) Frequency distribution-->Bar or pie
graph
(Bar chart ordered by size =&&
"Pareto chart"--not in text)
Pie &&only ok if showing all categories (part
of
whole)
+ no overlap of categories.
. Pie by hand? Template
handout
Relative Frequency of
colors in circle experiment? Any patterns? Variability?
Quantitative: Histogram,
Stem-and-leaf
("Stemplot"), Dotplot
(I will only
require
you to read, not make histograms by hand. You'll
Make
stemplots
and dotplots by hand)
Histogram bar area represents the number (or proportion)
of individuals (cases) in the interval ("bin") at the bottom of the
bar. "Living Histograms" handed around.
(Bar graph (categories) => Spaces between
bars. Histogram=> no spaces between.)
Pretest:
Restate #5 as histogram of 100 "6-volt" batteries tested for actual
voltage.
20 between
0&1 volt, 10 between 1&2, 30 between 2 & 3, 30
between 3&4, 10 between 4&5.
The proportion with voltage < 1 is 20%. The proportion
with voltage < 3 is 60%.
a) What proportion have voltage beween 1 and 3? b) What
proportion
have voltage > 3?
Stem-and-Leafs
are
a powerful hand tool. Handout
Unordered first, then ordered if necessary. By tens, then
split?
(Ex.:Class data)
Back
to back, comparing two groups. (p.51, #14)
Choosing a display (by hand):
A dot plot (p. 39) is
most useful for n = 3 to about 15-20, or when the data only fall on a
few
values (just make your scale axis & stack the dots up).
A stemplot is
good for continuous data, smeared around; you can do 100 values in 3-5
minutes.
Read
the rest, read the text, do the HW. We'll go over this briefly on
Monday
Describing: Pattern-- and
deviations
from it
Shape (symmetric,
or skewed (think smeared, or sliding) right or left),
(Humps:
uni-
or bi- modal (multi-) Two humps = two "causes"?)
Some special shapes:
uniform (p. 40) && J-shaped (#6 p.50)
bell-shaped
(Ch 6)
Center, Spread
(roughly now, Ch.5 numerically)
Outliers, gaps ? (different
groups, sources?) Look at
pulse
data. &&"Lurking variable"
What do we see?
What can we infer?
(Introduction)
Data source? Lurking variables?
Variability happens.
Things settle down on average (Pooled data on colors)
BUT
conclusions
are never certain.
Statistics will give us
a language for talking about uncertainty.
| Sievers home | Math151-Sp06/Daysp3.htm | 3pm | 2/3/06 |