Stat 401 B – Lecture 111First DayData Sheet – fill out and bring to lab tomorrowSyllabus – go over2The Big PictureWhat is statistics all about?3The Big PictureStatistics is about variability!Recognizing variability.Quantifying variability.Explaining variability.Stat 401 B – Lecture 124Statistical ThinkingAn appreciation of uncertainty and variability and their impact on decision making.Using the scientific method when approaching issues and problems.5Statistical ThinkingStarts with a question –Did cars and trucks made in 2004 meet the Corporate Average Fuel Economy (CAFE) standard?6Statistical ThinkingWhat data would help us answer this question?Stat 401 B – Lecture 137Population – all items of interest.Example: All vehicles madeIn 2004.Parameter – numerical summary of the entire population.Example: population meanfuel economy (MPG).Sample –afew items from the population.Example: 36vehicles.Statistic – numericalsummary of the sample.Example: sample meanfuel economy (MPG).8SamplingRandom selection from the population of interest.The lab tomorrow will look at what happens with “purposeful” sampling and random sampling.9A Word of CautionStatistical methods are very good at quantifying uncertainty introduced by random sampling.Statistics doesn’t help much if the population changes with time.Stat 401 B – Lecture 1410Political Opinion Poll1000 randomly selected likely voters are asked –“If the election were held today, for whom would you vote for President?11Political Opinion PollThe sample proportion indicating they would vote for McCain or Obama is a pretty good indication (within 3 percentage points) of the true proportion of the population of likely voters.12Political Opinion PollDoes that mean a poll taken today will predict the outcome in
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