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science of collecting, organizing, summarizing, and analyzing info to draw conclusions or answer questions. (sports stats, education stats, business, medicine, politics)
statistics
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info collected from individual
data
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entire group of individuals studied
population
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person/object being studied
individual
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subset of population selected to be studied
sample
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organizing/summarizing data by tables/graphs
descriptive stats
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use methods from sample, extend to population, measure reliability and answer questions
inferential stats
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numerical summary of population
parameter
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summary value based on a sample of individuals
statistic
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characteristic of individuals of interest
variables
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categorical, label, attribute, characteristic (ex: what's student major? gender? occupation? eye color? age categories? race?)
qualitative data
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numerical, arithmetic operations used (ex: age? # of textbooks, # of credits, length of time for activity, batting avg, temp, weight, length)
quantitative data
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based on a count (ex: # of people, # of credits, # of shoes)
discrete data
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measurement not countable (ex: weight, miles driven, Qual=SS#, zip code, phone number)
continuous data
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name only, no natural order (qual) (ex: major, political affiliation, gender, race, color)
nominal level of measurement
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have order (qual) (ex: age categories, education level)
ordinal level of measurement
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difference between 2 values is meaningful (ex: no absolute zero, temp, clock time, calendar years)
interval level of measurement
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ratios of values have meaning, absolute zero (ex: length of time 60 sec->15 sec=1/4, # of textbooks, # of credits, physical length)
ratio level of measurement
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amount of medicine, level of medicine in capsule
explanatory variable
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amount of time person takes to have relief
response variable
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no influence in explanatory or response variable
observational study
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intentional change in explanatory or response variable
experiment
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two or more explanatory variables are not seperated
confounding
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explanatory variable not considered in study
lurking variable
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look back in time, at past records
retrospective
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data collected over time
prospective
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