Fundamentals of Statistics Chapter 10 Unit A Fundamentals of Statistics

Essential Question How does statistics play a major role in modern society?

Population and Sampling

Population and Sampling

Definitions Statistics: data that describe or summarize something Population: complete set of people or things being studied Sample: subset of the population from which the raw data are actually obtained

Definitions Population parameters: specific numbers describing the characteristics of the population Sample Statistics: numbers describing characteristics of the sample found by consolidating or summarizing the raw data from the sample

Common Sampling Methods Simple random sampling: choose a sample of items in such a way that every sample of the same size has an equal chance of being selected Systematic sampling: use a simple system to choose the sample, such as selecting every 10th or every 50th member of the population

Common Sampling Methods Convenience sampling: choose a sample that is convenient to select, such as people who happen to be in the same classroom Stratified sampling: identify subgroups and then draw a simple random sample from each subgroup

Keep In Mind: No matter how the sample is chosen, the study is only successful if the sample is representative of the population Sample size is important (usually larger is better) We can never be sure that it is representative of the population, only a strong likelihood

Example: find population and sample Ag inspectors measure the levels of reside from three common pesticides on 25 ears of corn from each of the 104 corn- producing farms Anthropologists determine the average brain size (skull size) of early Neanderthals in Europe by studying skulls found at three sites in southern Europe

More definitions Bias: any problem in the design or conduct of the a statistical study that tends to favor certain results Observational Study: researchers observe or measure characteristics of the sample members but don’t attempt to influence or modify

Even more definitions Experiment: researchers apply a treatment to some or all of the sample and observe effects Treatment group: sample members who receive the treatment tested Control group: sample members who do not receive the treatment tested

Woah… even more defintions Placebo: lacks the active ingredient of the treatment being tested, but looks or feels identical to the treatment Placebo effect: patients improve simply because they believe they’re receiving a useful treatment Blinding: practice of keeping people in the dark about who is in the treatment group and who is in the control group

Are you kidding me? Case-control study: observational study that resembles an experiment because the sample naturally divides into 2 or more groups. Those who engage in the behavior under study (cases) and those who don’t (controls) Margin of error: used to determine a confidence interval that is likely to obtain the true population parameter.

How to use margin of error From (sample – margin of error) to (sample + margin of error) Using margin of error we can say we are “95% confident” Example: 52% of voters plan to vote for Trump. Will he win?

D19: Quick Quiz (in class?) D20: p.519-522 #9-20, 29-34, 47-50 Homework: D19: Quick Quiz (in class?) D20: p.519-522 #9-20, 29-34, 47-50