FINAL FOR STAT STUDY GUIDE - Chapter 1 Statistics a...

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Chapter 1 Statistics - a collection of procedures and principles for gathering data and analyzing information to help people make decisions when faces with uncertainty. Baseline risk -risk at a beginning time period under specific conditions. A representative sample of only a few thousand or hundred can give reasonably accurate information about a population of many millions. Population - collection of individuals about which information is desired Random Sample - a subset of the population selected so that every individual has a specified probability of being part of the sample. Sample survey - gather opinions or other information from each individual included in the sample. Margin of Error - 1/ n^(1/2) An unrepresentative sample, even a large one, tells you almost nothing about the population. Self-selected or volunteer sample - magazines, television stations, and Internet Websites conduct this kind of poll Cause and effect conclusions cannot generally be made on the basis of an observational study. Observational study - participants are merely observed and measured, or comparisons of naturally occurring groups. Confounding Variable – a variable that is not the main concern of the study but may be partially responsible for the observed results. Unlike observational studies, cause and effect conclusions can generally be made on the basis of a randomized experiment. Randomized Experiment- study in which treatments are randomly assigned to participant. the use of randomization is a key component when trying to make cause-effect conclusions. Statistically significant relationship or difference is one that is large enough to be unlikely to have occurred in the sample if there was no relationship or difference in the population. Datasets, Observations, and Variables Observational Unit- a single individual who participates in a study. Sample size – total number of observational units (n) Sample Data- when measurements are taken from a subset of a population Population Data- when all individuals in a population are measured Types of Variables Categorical Variables - consists of group or category names that don’t necessarily have any logical ordering EX: dominate hand, regular church attendance, opinion about legalization of marijuana, eye color (Tallies and cross-tabulations are used to summarize) Ordinal Variable- may be used to describe the data when a categorical variable has ordered categories EX: on a scale of 1 to 10, highest education degree earned, T-shirt size Quantitative variable, measurement variable, and numerical variable are synonyms for quantitative variable Continuous variable- can also be for quantitative data when every value within some interval is a possible result. EX: height
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This note was uploaded on 03/17/2008 for the course STAT 200 taught by Professor Barroso,joaor during the Fall '08 term at Penn State.

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FINAL FOR STAT STUDY GUIDE - Chapter 1 Statistics a...

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