Pol 51 FINAL study guide
Empirical theory
4 causal hurdles along route to establishing causal relationships:
1) Is there a credible causal mechanism that connects x to y?
2) Could y cause x?
3) Is there covariation between x and y?
4) Is there some confounding z variable that is related to both x and y and makes the observed association
between x and y spurious?
Game theory:
Nash Equilibrium 
A situation in which actors cannot act unilaterally to better their outcomes
Dominant strategy
The choice that benefits a player the most without taking the other into
consideration
Population parameter
a certain characteristic of a population that can be qualified as a number.
(ex. proportion of Californians who voted for Obama, Age)
Sample statistic
an estimation of a population parameter calculated from sample data.
Sample population congruence
Want sample to be representative subset of population. Incomplete
or inappropriate samples lead to sample bias an inaccurate conclusion about the population.
Sampling error
The discrepancy between an observed and a true value. The statistic most often
used to describe sampling error is called the standard error of the mean.
Distributions
Central tendency (mean median mode and standard deviation)
Skew (right or left)
Non symmetrical distribution, Positive or right skewed data has a larger tail to
the right and a negative of left skewed has a larger tail to the left. There are more frequency
scores at the higher ends of the distribution.
Kurtosis
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 Winter '08
 Ryan,John
 Statistics, Normal Distribution, Regression Analysis

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