IntroductiontoStatistics-Lecture.ppt

Misuse # 5- Percentages BM0129 - Business Problem Solving Misleading or unclear percentages are sometimes used. For example, if you take 100% of a quantity, you take it all. 110% of an effort does not make sense. Loaded Questions Order of Questions Refusals Correlation Causality Self Interest Study Precise Numbers Partial Pictures Deliberate Distortions BM0129 - Business Problem Solving Other Misuses of Statistics BM0129 - Business Problem Solving Recap Reviewed 13 misuses of statistics Illustrated how common sense can play a big role in interpreting data and statistics In this section we have: Topic 1.4Introduction to StatisticsDesign of Experiments BM0129 - Business Problem Solving BM0129 - Business Problem Solving Key Concept If sample data are not collected in an appropriate way, the data may be so completely useless that no amount of statistical tutoring can salvage them. BM0129 - Business Problem Solving Observational study observing and measuring specific characteristics without attempting to modify the subjects being studied Definition BM0129 - Business Problem Solving Experiment apply some treatment and then observe its effects on the subjects; (subjects in experiments are called experimental units) Definition BM0129 - Business Problem Solving Cross sectional study data are observed, measured, and collected at one point in time Retrospective (or case control) study data are collected from the past by going back in time Prospective (or longitudinal or cohort) study data are collected in the future from groups (called cohorts) sharing common factors Definitions BM0129 - Business Problem Solving Confounding occurs in an experiment when the experimenter is not able to distinguish between the effects of different factors Definition BM0129 - Business Problem Solving Controlling Effects of Variables Blinding subject does not know he or she is receiving a treatment or placebo Blocks groups of subject