## Tues Sep 9 - Statistics Lecture Notes

• introductions
• questions
• algebra and arithmentic ( review or heads-up )
• percent : 16% = 16/100 = 0.16
• exponents : 10-3 = 1/(103) = 0.001; (xa)(xb) = x(a+b) ; 250.5 = 5
• function notation : sqrt(16) = 4 means
"Doing the square root thing to the number 16 gives 4."
• expanding and collecting terms :
(a+b)3
= (a+b)(a+b)(a+b)
= a (a+b)(a+b) + b(a+b)(a+b)
= [ aa(a+b) + ab(a+b) ] + [ba(a+b) + bb(a+b)]
= aaa + aab + aba + abb + baa + bab + bba + bbb
= a3 + 3a2b + 3ab2 + b3
• lists of numbers : tests = {65,70,70,85,85,90,90,90}
• definitions from chapter 1 - discuss briefly
• population - all of the things under consideration
• sample - some part of a population
• random - particular kind of selection process with given probabilities (typically uniform) for the outcomes
• biased - not random
• descriptive statistics - using numbers to summarize a completely known population
• inference - deriving numbers from a sample and using them to make educated guesses about the population they came from.
• data - the information collected for a given project.