Monday, January 10

	Topic: Statistical Summaries
	Topic: Distributions
	Read: Utts 7
	Read: Utts 8
	Act: How Many Raisins?
	Due: HW #2 @ hw01.shtml

	Vocab:
		mean, median, mode, outlier, range, stemplot, histogram, %%
		shape, symmetric, bell-shaped, unimodal, bimodal, skewed, %%
		five-number summary, quartile, boxplot, interquartile range, %%
		variance, standard deviation, frequency curve, normal curve, %%
		proportion, percentile, standardized score, z-score, %%
		standard normal distribution, "68-95-99.7 Rule" 

	Where are we now?
	    many problems with statistical studies are not mathematical
		7 critical components
		    Pam Plantinga left job because she was told what to find

	    you can't do good statistics unless you start with good data
		individual issues
		    four issues: validity, reliability, bias, variablility
		    measurement 
			must decide what and how to measure -- not always easy
			ask about any problems with survey 1
		    wording 
			dealing with people is especially hard
			do you own stock cartoon
		    proxies (validity/reliability trade-off)

	        sampling/assignment issues
		    good samples are representative and large enough
			1/root n rule
		    experiment vs. observation, the role of treatment
		    randomness used to reduce bias

	    moving into a phase of "what do we do with all this data?"

	but first ...
	... Ethics of experiments
	    informed consent
		use of doctors in physicians health study
		kids in art experiment

	    human subjects & review boards
		Stanley Milgram (Yale): shock and memory
		    done 1960's, probably not doable today
		Penny's data collection in grad school
		
	    risk: cost/benefit analysis
		reasonable hope, reasonable doubt criteria for clinical trials
			(did friday)

	    Some specific examples and issues
	  	Nazi data
		    give them article (2 versions) and then discuss
			from Bouma's class
						Yes	No
				good use	 6	 2  (1 of 2 struggled)
				criticism	 5	 3

		    twins studies -- ideal matched pairs?
		    

	    	PHS used only middle-aged men, what about women? minorities
		    1 in 5 men has heart attack before age 65
		    1 in 17 women has heart attack before age 65
			(did friday)
		
		AIDS and slow process of clinical trials
		    measuring easier but less reliable things
		    pressure to release drugs before effectiveness demonstrated
			(mentioned friday, mention again)

		domestic violence: warn and release or arrest
		    can a randomized experiment be done?  [no informed consent]

	Raisins & entry of data not yet enterred from survey 1

	Looking at the data: stemplots, histograms
	    choosing bin-size
	    subdividing stems
	Measures of center -- what is a typical value? mean, median, mode
	    what is unusual? outliers
	Measures of spread
	    range, standard deviation
	Five-number summary & boxplots

	Some shape descriptions 
	    symmetric, skewed, bell-shaped, unimodal, bimodal

	Intro to frequency curves and cummulative probability (proportions)
	    generalization of 5-number summary
	    deciles, percentiles from standard tests
	    
	Normal distributions
	    symmetric, bell-shaped, determined by mean and standard dev.
	    Empirical Rule: 68-95-99.7
	    standardized scores (z-scores)
	    charts and computers to get other values (chart on page 137)

	    examples of approx. normal distributions
		height (male 18-74)	N(5'9",3") = 	N(69,3)
		height (female 18-74)	N(5'3.5",2.5")=	N(63.5,2.5)
	   	 
		height (male 18-24)	N(5'10",3") = 	N(70,2.8)
		height (female 18-24)	N(5'4.3",2.6")=	N(64.3,2.6)
	   	 
		height (male 11)	N(146cm,8cm) = 	N(57.5,3.15)
	   	 
		weight (male 18-24)	N(162,29.1) 
		weight (femail 18-24)	N(134,27) 
	   	 
		1994 SAT mean Verbal = 423, 7% above 600, 42% below 400
			approx s.d. 120
			now renormalized to N(500,100)
			what percent score 800?

		1987 CA women's salaries  mean=11,600; s.d.=10,500