| Hand in (all from Moore text unless otherwise noted). p. 28, 1.29 spam Calculate how much "other" spam there is, and Use your pie template to make a pie chart. (The pie chart is only "legal" if every item falls into only one box. I wonder: is a Viagra ad Adult, Health, Leisure, or Products? Footnote, google: http://www.clickz.com/showPage.html?page=3321901. Health, I think. ) p. 18, 1.9 foreign born (reading histos) p.28, 1.30 fruit, 1.31 stocks (reading histos) p. 31, 1.35 CO2 stemplot. I would use whole tons as stems, tenths as leaves, see how it looks. Truncate, don't round, for speed. Don't bother to put in order. p. 56, 2.13 (yes.) From this dataset (IQ), make a Dotplot. Is there anything odd about the data set? Don't do anything else. p. 31, 1.34 doctors. Do a stemplot, not a histogram. Use hundreds as stems, and split them as on p. 21. p. 33,1.37 study time back to back, or do side by side on the same scale, like fig. 2.5, p. 55. (Good stems: maybe by 2's: 80-90, 100-110, 120-130, etc., so stems are 0*, 0t, 0f, 0s, 0., 1*, 1t, 1f, 1s, 1., 2*, 2t etc., and 140 goes on the 1f stem as a 4, 210 goes on the 2* stem as a 1, 30 goes on the 0. stem as a 3, 0 goes on the 0* stem as 0, or is "low". Splitting by 5's (p. 21) might be good enough. ) Notice the mental rounding of the responses, to quarter hours if not to ten minuteses. Makes "Granular" data. |
Read, to discuss p.30,1.32 name that variable p.34,1.40 coins (skewed left) |
Optional
|
Introduce yourself to your
neighbors--sides,
front & back. Check for Homework questions?
Hand in Info sheets, Math pretests if you
didn't. Sign in.
If you didn't last time, take your pulse, Pick a
card!
Handouts: Pie template.
Stemplot.
Honor code:
This community of learners is a rare and fragile thing. Trust is
the foundation of its structure. Betraying the trust damages the
whole community. Please do not betray my or your fellows' trust,
and I will do my best to reciprocate. The flip side of this is
that
if you do betray our trust, I will definitely pursue it in Community
Court.
Clinic hours are not all in yet, but our special assistant Anna
Radlowski will have her hours
Tues 9:30am-11:00am
Tues 1:30pm-2:30pm
Wed 9:30am-10:30am
Thurs 9:30am-11:00am
Thurs 1:30pm-2:30pm
Thurs 7:00pm-9:00pm
Data: Numbers
(usually)
in context: What, Who (how
many),
Why? When and Where? How?
Context for height, hair
color,
shoe size, pulse rate: Any problems with the way I did it?
Smoking and brain injury
articles?
Variable (possible values), individuals (cases)
Categorical
(ordinal--has
natural order or nominal--just
names) Ordinal/nominal not in text!
or Quantitative
(can add, average--measured on a ruler-type scale) Units?!
("calories"?)
Distribution of
one
variable: what values, how many (or what proportion) of each.
(Frequency
table)
Graphical summaries of data: Area
represents proportion.
Categorical:
Bar or pie graph (Bar chart ordered by size = "Pareto
chart")
Pie only ok if showing all categories.
What about smoking and brain injury? What
were the merits of each display?
Quantitative: Histogram,
Stemplot (Stem-and-leaf), Dotplot
(I will only
require
you to read, not make histograms by hand. You'll
Make
stemplots
and dotplots by hand)
Will Discuss Friday:
Pretest:
Restate #5 as histogram of 100 "5-volt" batteries tested for actual
voltage.
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?
Histogram can change somewhat
depending on intervals you choose.
Moore Applet (
http://bcs.whfreeman.com/bps4e)
. or use disk in book) One Variable Statistical
Calculator, text pp. 11-13, Ta 1.1
Stemplots
(Stem-and-Leaf)
are a powerful hand tool. Tally, value
added. Handout
!!Unordered first,!! then ordered if
necessary. By tens, then
split?
Back
to back, comparing two groups. (or side-by-side on same
scale, cf. p55 fig. 2.5)
Data from class so far
Describing:
Pattern-- and
deviations
from it
Shape (symmetric,
or skewed (think smeared, or sliding) right or left),
(&& bell-curve
(Ch 3), J-shaped (fig.1.15a p.31))
(Humps:
uni- or bi- modal (multi-) Two humps = two
"causes"?)
Center (roughly--half on each side) , Spread
(smallest to largest)
Outliers, gaps ? (different
groups, sources?)
Dot plot: Draw a horizontal axis, pile up dots at the
appropriate points.
Note top of p. 49,
fig. 2.3, use of a dot plot to
display a data set
of
size n = 7.
Choosing a display (by hand):
A dot plot is
most useful for n = 3 to about 15-20, or when the data only fall on a
few
values (just stack the dots up).
A stemplot is
good for continuous data, smeared around; you can do 100 values in 3-5
minutes.
What do we see?
What can we infer?
(Introduction)
Data source? Lurking variables?
Variability happens.
Things settle down on average, BUT conclusions are never certain.
Statistics gives us a
language
for talking about uncertainty.
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