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32 Cards in this Set
- Front
- Back
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Inferential statistics
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ability we have to take sample data and infer to population
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Census is
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entire population
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p value
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probability that 50% shows a true population parameter
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variables
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stuff that we quantify
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2 discrete variables
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nominal/categorical and ordinal
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2 continuous variables
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interval and ratio
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degrees (temp) is a(n)
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interval variable
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kelvin (temp) is a(n)
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ratio variable because it has an absolute 0
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kurtosis
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too fat/too thin
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p (rho) is a
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parameter
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hypotheses tests allow us....
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they allow us to talk about EVIDENCE OF CAUSALITY, NOT PROOF
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Don't use t test or ANOVA with
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continuous; may lose data or something like that?
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t and f tests aren't
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aren't necessarily for normal distributions
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_______ is the only central tendency measure that makes sense for categorical variables
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mode
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formula for standard deviation
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s = square root of E(x-xbar)^2/n
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z score formula for a sample
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z = (x-xbar)/Sx
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Raw score formula of SSx
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EX^2 - ((EX)^2)/n))
Divide this all by n and take the square root to get the standard deviation (no square root for variance) |
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t test is Pearson's r with
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experiment
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restriction of range is ______ the relationship
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underestimating
its looking for elongation |
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If cut off middle of scatter plot, you are _____ the relationship
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overestimating
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r^2 is
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the coefficient of determination
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If r=.42..and r^2=.16, it means...
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we can explain 16% of the differences in x ...i think
R2 is a statistic that will give some information about the goodness of fit of a model. In regression, the R2 coefficient of determination is a statistical measure of how well the regression line approximates the real data points. An R2 of 1.0 indicates that the regression line perfectly fits the data. ask about this |
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1 - r^2
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coefficient of nondetermination (we cannot explain 84%?)
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xbar is ________ than population mean
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xbar is usually smaller than population mean so sometimes its n-1 in the denominator for mew
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Regression of y on x...standard score formula
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z1y = rzofx ..z1y is z score of y (prediction) and z of x is z score of x
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When r = 1
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mean of x is predicting mean of y
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If r = 1 and zx=1, then
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z1y=1
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Syx will tell us _______
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68% within 1 SE
it is the standard error of estimate |
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If Syx is small, it is _____
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hugging line pretty closely
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Formula of Syx
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Syz = square root of E(Y-Y1)^2/n
and Sy times the square root of 1-r^2 |
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3 assumptions of Syx
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1. Linear association (obvious but maybe its parabolic)
2. Homosledasticity (spread of points on regression line are same no matter on x axis) 3. Normal distribution on Y around Y1 |
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Regression to the mean could be a _____
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confounding variable
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