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37 terms

Statistics Exam 1

STUDY
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Discrete Variables
Variables that can take on a finite set of values (ending)
Continuous Variables
Variables that can take on an infinite set of values (non-ending)
Real Limits
An extra tenth, midway between the given value and the next lower/higher value (9.87 = 9.865/9.875)
Population
An entire set of possible observations that may be made
Sample
A collection of numbers drawn from a population
Independent Variable
The variable that is varied or manipulated by the researcher
Dependent Variable
The response that is measured
Experimental Study
Describes behavior with identifying the cause
Non-experimental Study
Describes behavior but does not identify causes
Quasi-experiment
An observational study with subjects that are already grouped from existing categories
Nominal Scale
Mutually exclusive categories (category)
Ordinal Scale
Mutually exclusive categories and logical natural order (ranks)
Interval/Ratio Scale
Mutually exclusive categories, logical and natural order with equal differences between values
Histogram
Touching bar graph with interval/ration data
Bar Chart
Non-touching bar graph with nominal/ordinal data
Frequency Polygon
Line graph with interval/ratio data
Unimodal Distribution
One peak in the graph
Bimodal Distribution
Two peaks in the graph
Symmetrical Tails
Equidistant lengths from the mean
Skewed Tails
Differing lengths from the mean
Kurtosis
How pointed or flat the curve is
Advantages of Mode
Unaffected by extreme scores, is an actual score in the distribution, can use mode with all data
Disadvantages of Mode
May not represent data well, can easily be affected by one or two scores
Advantages of Median
Unaffected by extreme scores, can use with ordinal or interval/ratio data (can represent skewed data)
Disadvantages of Median
May not represent data well, value you may not exist as a real score, cannot use with nominal data
Advantages of Mean
Every point contributes to the mean, can be used in equations, unbiased estimate of population
Disadvantages of Mean
Influenced by extreme scores, can be used with interval/ratio, value may not exist in the data
Mode = Mean = Median
Any normal distribution
Use Mode with...
Nominal, Ordinal, Interval/Ratio data
Use Median with...
Ordinal, Interval/Ration data
Use Mean with...
Interval/Ratio data
Variability
Indicates the spread of distribution and the degree to which scores are clustered about the mean
Measures of Variability
Range, Standard Deviation, Variance
Degrees of Freedom
The number of values in a data set that can vary
Inflection Points
A point where a line changes from concave to convex
Percentiles
Values that divide the distribution into 100 equal parts
Percentile Rank
A particular person's rank relative to the reference group