# Shared Flashcard Set

## Details

Quantitative Methods
Note cards for Quantitative Methods
19
Political Studies
10/25/2011

## Additional Political Studies Flashcards

Term
 Standard Error Formula
Definition
 SE = s/√ns= standard deviationn = sample size
Term
 Pearson's r correlation coefficient formula
Definition
 r = N∑xy-(∑x)(∑y)/√[(N∑x2-(∑x2)] • [N∑y2-(Σy)2]
Term
 Regression Formulas; Calculating b
Definition
 b = ∑(X-X‾) (Y-Ȳ) / ∑(X-X‾)2
Term
 Regression Formulas; calculating a
Definition
 a = ∑Y - b∑X / N = Ȳ - bX‾
Term
 Operationalization
Definition
 Strictly defining variables into measurable factors.  The process defines fuzzy concepts and allows them to be measured, empirically and quantitatively.
Term
 Heteroscedasticity
Definition
 Meaning "differing variance;" this occurs if the collection of random variable contains sub-populations that have different variabilities than others.
Term
 BLUE
Definition
 Best Linear Unbiased Estimate
Term
 Basic assumptions of OLS regression
Definition
 1) Linearity--the relationships between the predictors and the outcome variable should be linear. 2) Normality--the erros should be normally distributed-technically normality is necessary only for hypothesis tests to be valid. Homogeneity of variance (homoscedasticity)--the variance should be constant--mean of zero. 4) Independence-- The erros associated with one observation are not correlated with the errors of any other observation.
Term
 Dependent variable
Definition
 The variable that the researcher is trying to explain.
Term
 Independent variable
Definition
 The explanatory variable, that is, the hypothesized or presumed cause of the changes in the value of the dependent variable.
Term
 Predicted value
Definition
 The values predicted by a statistical model which was fit to the data. For example, when fitting a line to values for X and Y, the predicted values refer to the location of the line at a given value of X.
Term
 Model
Definition
 A likeness of reality, consisting of symbols and/or concepts, that represents the characteristics of the phenomenon.
Term
 Fitted value
Definition
 The values predicted by a model fitted to a set of data.
Term
 P value
Definition
 Associated with a test statistic. It is "the probability, if the test statistic really were distributed as it would be under the null hypothesis, of observing a test statistic [as extreme as, or more extreme than] the one actually observed."
Term
 P-value
Definition
 The probability of obtaining a test statistic at least as extreme as the one actually observed, assuming the null is true.
Term
 T-Test formula
Definition
 Z = X¯ / (σ/√n)X¯ = sample mean; n = sample size; σ = population standard deviation
Term
Definition
 A modification of R2 that adjusts for the number of explanatory terms in a model.  Penalized for adding more variable to the model.     R¯2 (R-bar squared)
Term
 -.7657 ; -.7657*
Definition
 -.7657 would indicated a strong negative correlation. -.7657* would indicated a strong negative correlation and the star indicates the number is statistically significant
Term
 A regression coefficient
Definition
 Whether or not the number is positive or negative determines whether there is a positive or negative correlation between the independent and dependent variable. The absolute value of the number determines the strength of the correlation.
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