Statistics

the study of how to collect, organize, analyze and interpret info, Population
 the collection of individuals or items of interest, Census

measurements from an entire pop are used, Sample
 the subset of the pop on which we take measurements, Data
 the measurements we collect, Individuals

the objects described by a set of data, Variable
 any characteristic of and individual that can take different values for different individuals, Descriptive stats

methods of summarizing a set of data (no errors because you are summarizing the data you have) ex: sports stats, avg. GPA for students, car sales for the yr.,
# of students who live in Lex., Inferential stats
 methods of making inference about a pop based on the info in the sample;
collect data from a subset or
sample of pop and use to estimate pop (is error because you don’t have all data, you have a subset of data) ex: presidential approval rating, Observational
study
 observes individuals and measures variables of interest but doesn’t attempt to influence responses ex: outcome of election predicted by polls, Sample
survey when data is collected by asking questions and recording answers; most common type of observational study ex: opinion polls, consumer surveys,
teacher evals, Experiment
 deliberately imposes some treatment on individuals to observe responses, Simulation
 numerical facsimile of real world phenom;
not used unless necessary, expensive) ex: crash tests, Bias
 prejudice in one direction, Convenience sampling
 uses results or data that are conveniently &
readily obtained, can be extremely biased and shouldn’t be generalized to the overall pop or for inferential data, Voluntary response sample
 common type of
convenience sample that is selected by subjects volunteering, typically over represents people with strong opinions ex: comment cards, Random sample

sample determined completely by chance, is a representative sample, Simple random sample
 sample of n measurements from a population selected in such a
manner that every sample of size n from the population has equal probability of being selected, most common and all course is based on Stratified sampling

population is divided into at least two distinct strata or groups, a simple random sample is drawn from each, Systematic sampling
 select a random starting
point, select every fourth person in the sample, Cluster sampling
divide pop onto sections, randomly select the sections or clusters, Variability
 describes the
spread of values; we want the possible values of a statistic to not include bias and have a small amount of v.; to eliminate bias use random sampling; to
control v. use a larger sample, Statistic
 a numerical characteristic of sample, Parameter
 a numerical characteristic of a population, Margin of error
 can be
calculated from the sampling variability; We can say with 95% confidence that the amount by which a proportion obtained from a sample will differ from
the population proportion will not exceed
Suppose you take a sample of 1600 adults and 800 enjoy amusement park rides. the sample proportion that