# Shared Flashcard Set

## Details

for Social Sciences
46
Other
12/31/2009

Term
 law of parsimony
Definition
 include the important predictors in your model without attempting to add every explanation
Term
 Occam's razor
Definition
 the simplest explanation is usually the best one
Term
 quantitative variable
Definition
 those in which the coding of the variable is a close reflection of their meaning
Term
 continuous variable
Definition
 (interval) can assume any real value, i.e. temperature
Term
 discrete variable
Definition
 (count data) can only assume integer values, cannot be divided into fractions, i.e. number of children
Term
 qualitative variables
Definition
 those whose numerical representation in the data set simply classifies mutually exclusive values of the variable, but those numerical representations are substantially less meaningful than what is found with quantitative variables
Term
 ordinal variables
Definition
 qualitative variables in which the numbers represent a hierarchy of values. i.e., attitudes or grade in school
Term
 nominal variables
Definition
 qualitative variables in which the numeric values assigned to values are merely placeholders, i.e. race
Term
 dichotomous variables
Definition
 (binary variables) variables in which there are two and only two possible outcomes
Term
 dummy variables
Definition
 binary variables that have been coded with 0 and 1
Term
 indicies
Definition
 new variable created by adding up a number of variables together
Term
 scale
Definition
 new variable created by combining (sometimes weighting) variables to create something new altogether, i.e. socioeconomic status
Term
 factor
Definition
 underlying construct of the components in a scale
Term
 latent variable
Definition
 indirectly measured construct, i.e. socioeconomic status
Term
 multicolinearity
Definition
 a condition created when two or more variables measure the same underlying construct
Term
 standardization
Definition
 refers to any one of a number of mathematical techniques for transforming variables so that they are in a single metric
Term
 internal reliability
Definition
 2 or more variables are measuring the same thing (score on one variable should predict the score on another variable0
Term
 Cronbach's Alpha
Definition
 measures the internal consistency of several variables. Alpha reliability ranges from 0 to 1, where 1 is perfect internal reliability and 0 is the variables do not measure the same thing at all. (alphas greater than .7 are generally considered to have enough internal relaibility that scaling is warranted
Term
 exploratory factor analysis (purpose)
Definition
 1) can be used to see if a single variable can be used to replace multiple variables2) can determine if several variables can be scaled together3) detect clusters of variables
Term
 3 types of factor analysis
Definition
 1) Exploratory factor analysis (EFA)2) Principal component analysis (PCA)3) Confirmatory factor analysis (CFA)
Term
 Pearson's correlation coefficient
Definition
 used to understand how variables are related to each other; measured from -1 to 1 (negative number=negative association; positive number=positive association)
Term
 factor matrix
Definition
 produced by EFA; measures the combination of the linear composites and the structure coefficients
Term
Definition
 in a factor matrix, the amount of weight you would give a variable if you were going to put it in a scale
Term
 3 stages of factor analysis
Definition
 1) Selection2) Extraction3) Rotation
Term
 Selection stage of factor analysis
Definition
 determine the number of factors that are meaningfully represented by the variables
Term
 eigenvalue
Definition
 in factor analysis, indicates the variance accounted for by each underlying factor
Term
 Kaiser- Guttman rule
Definition
 in selection of FA, the total number of factors represented by a set of variables is equal to the number of eigenvalues greater than 1
Term
 scree plot
Definition
 in selection stage of FA, a graph with the factors on the x axis and the eigenvalues on the y-axis. The scree that occurs after the curve bends is simply error variation and does not represent true factors
Term
 Extraction
Definition
 2nd stage of FA, the process by which we account for variance
Term
 best method for FA extraction
Definition
 principal axis factoring with iterated communalities (least squares)- best approach, especially if smaller sample size
Term
 Rotation
Definition
 3rd stage of FA, extremely complex mathematical procedure that requires you to think in crazy dimensions. Basically, it rotates the axis to place it nearer to the data points
Term
 Orthogonal
Definition
 Type of rotation in FA; assumes factors are uncorrelated to each other
Term
 Oblique
Definition
 type of rotation in FA; assumes correaltion
Term
 Rule of thumb when determining which variables load on which factors in FA
Definition
 1) factor should have at least 4 variables2) each variable should load close to or higher than +/- .5
Term
 kurtosis
Definition
 a measure of whether the data are peaked or flat relative to normal distribution
Term
 summary statistics
Definition
 mean and standard deviation
Term
 inferential statistics
Definition
 show bivariate differences of means or proportions
Term
 which inferential statistics to use if 1)using percents or proportions2)means
Definition
 1) Pearson's Chi-Square2)Student's t-test or an f-test derived from ANOVA
Term
 indicator variable
Definition
 how most nominal and ordinal data are entered into models; a dummy variable is created for each category of the variable
Term
 Student's t-test
Definition
 used to compare 2 (and ONLY 2) means to see if they are statistically different from each other.Most often use the two-tailed t-test where Ho= means are equivalent and Ha= means are different. First, must test for equal variance. p< .05 means we are 95% sure that the difference in means observed is not simply due to sampling error.
Term
 Robust test for equal variance
Definition
 used before a t-test can be conducted to determine whether the two groups have equal variance on the variable under question. Want p > .05
Term
 Levene's test for equal variance
Definition
 most common used robust test for equality of variance; (w0) ONLY indicates whether you have equal variance, not if you have statistically significant differences of means. Ho= equal variance; ha= unequal varaince. want p> .05
Term
 ANOVA f-test
Definition
 (Analysis of variance f-test): used when comparing the means of three or more groups. One-way ANOVA- ho= all means are equal; Ha= at least two groups have different means. If p is significant, then must conduct a post-hoc test
Term
 3 types of post-hoc tests
Definition
 Used after geting a significant p value in a one-way ANOVA.1) Bonferroni2) Scheffe3) Sidak
Term
 Barlett's test for equal variance
Definition
 Addresses the major limiting assumption of ANOVA which assumes that the population variances are equal. Ho= equal varainces, Ha= unequal variances. Pant p > .05 so we fail to reject the Ho
Term
 Correlation
Definition
 a statistical technique used to measure and describe a relationship between two continuous variables.
Supporting users have an ad free experience!