# Shared Flashcard Set

## Details

RSCH Methods (Public Affairs)
Exam 1
21
Political Studies
10/05/2012

Term
 Nominal Measure
Definition
 - Qualitative variables - No special order
Term
 Ordinal measure
Definition
 -categories have an order - distance between categories unknown (ie Dem- Mod- Rep)
Term
 Interval measure
Definition
 -Numerical values with known, meaningful distances- (monetary values)-(percentages)
Term
 3 Objectives of Statistics
Definition
 Design-how to answer the research QDescription - (what does the data mean)Inference- (predictions, external validity)
Term
 Ecological Fallacy
Definition
 Inferring individual-level relationships from aggregate-level results.
Term
 Random Error
Definition
 Haphazard distortions
Term
 Systematic Error
Definition
 Chronic Distortions
Term
 reliability
Definition
 the degree to which an instrument consistently measures a concept
Term
 validity
Definition
 the degree to which a measure is likely to produce a concept’s true value
Term
 4 steps of operationalization
Definition
 1) Clarify the Concept2) Operationalize the concept as something measurable and concrete 3) Gather Data4) Construct Variables
Term
 Indicator
Definition
 Concept = Error
Term
 histogram
Definition
 A graph that displays the data by using vertical bars of various heights, where the heights represent the frequencies
Term
 weakness of mean
Definition
 The mean is sensitive to the influence of a few extreme observationsAlso, a skewed distribution (with or without outliers) will pull the mean towards its long tail
Term
 the median
Definition
 The middle of the data (i.e. the 50th percentile)Put the data in order, then choose the central data pointIf n is even, take the mean of the middle two data points
Term
 the mode
Definition
 The most frequently occurring valueThe most likely outcome among your data values
Term
 Resistant measure
Definition
 limits the influence of outliers and its value does not respond strongly to changes in a few observations (no matter how large)
Term
 Standard Deviation
Definition
 The most common measureThe standard deviation is approximately equal to “how much the average observation differs from the mean”When this number is big, we’d say the average observation tends to lie far from the mean  the data are very spread out
Term
 the Empirical Rule
Definition
 About 68% of the data will fall within 1 standard deviation of the sample meanAbout 95% will fall within 2 standard deviationsNearly all data will fall within 3 standard deviations
Term
 probability
Definition
 is a numerical measure of the likelihood that a specific event will occur.
Term
 4 assumptions of standard normal distribution
Definition
 1) The total area under the curve is 1.0.2) The curve is symmetric about the mean.3) The two tails of the curve extend indefinitely.4) Empirical Rule (covered last class): appx 68%- 95% -99% of observations fall within 1, 2, and 3 standard deviations from the mean respectively
Term
 standard normal distribution
Definition
 The normal distribution with μ = 0 and σ = 1
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