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27 Cards in this Set
- Front
- Back
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variable
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any characteristic of interest, varies from individual to individual
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quantitative variable
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measurements or counts of the data
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categorical variable
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places the data into groups/categories
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distribution
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list of all possible values of variables and how often
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data displays for categorical data:
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pie charts, bar graphs
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shape of distribution:
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symmetric, skewed right, skewed left, flat
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describing a histogram?
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shape, center, variability (spread)
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mean
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average of all values in a data set
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median
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value in the middle of a data set ordered from low to high
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mean=median
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symmetrical
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mean<median
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skewed left
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mean>median
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skewed right
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mean is affected by __________ but the median is not
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SKEWED DATA
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standard deviation
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average distance between mean and data
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population
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entire group you want to study (usually can't do that b/c of size thus, sample!)
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simple random sample
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draw a random sample of size in from the population
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stratified random sample
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set of simple random sample each taken from a subgroup of population
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surveys
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major means of data collection
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undercoverage
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when you had a plan to select a sample from population but an entire group was left out of the plan
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convenience/volunteer sample
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you don't set a true plan for a really random survey, just put out an invitation
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nonresponse
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an individual was selected for sample but didn't participate
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response bias
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individual responded untruthfully
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bias
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systematic favoritism of individuals or their responses
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scatterplot
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shows the relationship between two quantitative variables
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correlation
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measures strength and direction of linear relationship
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statistical significance
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large enough difference that changing subjects yields similar results.
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confounding/lurking variable
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a variable that has an important effect but was unaccounted for.
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