STATSWeekFourNotes.pdf Stats 1350
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This 6 page Class Notes was uploaded by Alyssa Leathers on Friday February 6, 2015. The Class Notes belongs to Stats 1350 at Ohio State University taught by Ali Miller in Winter2015. Since its upload, it has received 108 views.
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Date Created: 02/06/15
STATS 1350 2615 1222 PM Week Four Chapters Nine and Ten Do Numbers Make SenseGraphs good and bad Review Problems 1 Bias Sometimes the driver is sitting in the truck when it is weighed 2 Reliability When the same truck is weighed independently more than once the truck scale will give different values 3 Validity reasonable representation When the legislature established the road tax they intended to tax according to the value of the goods being shipped not according to the weight TrueFalse Review 1 Measurement systematically underestimates a parameter we say this measurement has high variability False biased 2 Sample of adults in US Contact IRS and random list Choose randomly amongst people who filed taxes last year This a nonsampling error False sampling errorunder coverage 3 Divide subjects into two groups go to gym once a week and those who don t This is example of completely randomized design False block design 4 Taking many measurements not just one is a good way of reducing bias False variability Two interesting and relevant current studies 0 Placebo Power the superior efficacy of expensive fake drugs 0 Treatment 0 Posting a lot of selfies doesn t send a good message Do the numbers or claims make sense Bombarded with information claims are made about products terms like scientifically provenquot and results grantedquot make complex info easy to understand and visualize Sketchers toning shoes commercial 0 What claims are being made in this ad 0 The shoe increases fitness somehow how o What kind of info would we need to better assess if these claims might be true 0 An experiment that compares two treatments One wearing sketchers Two wearing traditional shoes 0 Do toning shoes really work 0 Studies have been done significant difference between sketchers and normal shoes placebo Sketcher lawsuit for their commercial Cheerios commercial 0 What is cheerios claim 0 People who tend to choose whole grains tend to weigh less than people who don tquot 0 Possible lurking variables 0 What kind of milk 0 Exercise habits o Priceincome o Other dietary decisions 0 Better Asses this claim 0 Find other evidence that backs up the claim or refuses the claim 0 Study shows 0 One group all grains vs Group two no grain o Is this difference significant Depends on sample size variability stand dev of sample averages confidence intervals hypothesis tests 0 Both groups lost weight not clear Purina Puppy Chow Commercial 0 What claim 0 Extends lifespan of dog by 18 healthy years 0 Feed to ideal body conditionquot dog how will owners know Trident Gum Commercial 0 Claim 0 45 80 dentist survey would recommend trident sugarless gum for their patients Who are these dentists What questions were asked of the dentists Sample size How much does a dentist know about gum Why would the dentists have a preference Validity 0 Significance comparison to other gums Review Problem Reasonable margin of error Use rule of thumbquot should be between the range 1 square root of n OOOOOO Graphs Spacing Scales Variables and Distributions Variables characteristics of individuals height yield length age etc 0 Distribution of a variable tells us what values it takes and how often it takes these values Data Tables 0 Summarize data and show distribution of variables 0 Could include counts rates 0 Clearly labeled including units 0 Include source of data where did this come from valid accurate 0 Example 0 Possible outcomes 0 Counts 0 Variable Kinds of Graph 0 Categorical 0 Individual into one of several groups gender etc 0 Bar graph bars don t touch 0 Pie chart sum to 100 0 Various categories x axis 0 Y axis of observation 0 Quantitative 0 Numerical Value 0 Adding on averaging the values makes sense height etc How to make good graphs 0 What are we counting Label everything Don t be an artist Report info Keep it simple 0 Verification peer review Line graphtime series plots 0 X axis time 0 Y axis measurement 0 Measures change over time General trendquot 0 Overall increaseoverall decrease 0 Never perfect Line graph what to look for 0 Big pictureoverall trend 0 Seasonal variation Recurring patterns Periodicreporting Omitting zero 0 Consistency importance 0 Severity of trend OOOO 2615 1222 PM 2615 1222 PM
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