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

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Cards

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 Q
Description - (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 Concept
2) Operationalize the concept as something measurable and concrete
3) Gather Data
4) 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 observations

Also, 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 point
If n is even, take the mean of the middle two data points
Term
the mode
Definition
The most frequently occurring value
The 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 measure
The 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 mean
About 95% will fall within 2 standard deviations
Nearly 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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