SCMA 350 Study Guide Questions with Correct
Answers
Population
Includes all objects of interest in a study— people, households, machines, etc.
Sample
Representative subset of population, usually chosen randomly
Variable (or field or attribute)
Attribute or measurement of members of a population, such as height, gender, or salary
Observation (or case or record)
List of all variable values for a single member of a population
Data Set
(Usually) a rectangular array of data, with variables in columns, observations in rows, and
variable names in the top row
Data Types
Several categorizations are possible: numeric versus categorical, discrete versus continuous,
cross-sectional versus time series; categorical can be nominal or ordinal
Dummy variable
A variable coded 1 or 0: 1 for observations in the category, 0 for observations not in the
category
Binned (or discretized) variable
Numeric variable that has been categorized into discrete categories called bins
, Concatenate
String together two or more pieces of text
Variance
Measure of variability; essentially the average of squared deviations from the mean
Standard Deviation
Measure of variability in same units as observations; square root of variance
Mean absolute Deviation (MAD)
Another measure of variability; average of absolute deviations from the mean
Histogram
Chart of bin counts for a numeric variable; shows shape of the distribution
Box plots
Alternative chart that shows the distribution of a numeric variable
Time Series Graph
Graph showing behavior through time of one or more time series variables
Crosstabs (or contingency table)
Table of counts of joint categories of two categorical variables
Comparison problem
Comparing a numeric variable across two or more subpopulations
Stacked or unstacked data formats
Answers
Population
Includes all objects of interest in a study— people, households, machines, etc.
Sample
Representative subset of population, usually chosen randomly
Variable (or field or attribute)
Attribute or measurement of members of a population, such as height, gender, or salary
Observation (or case or record)
List of all variable values for a single member of a population
Data Set
(Usually) a rectangular array of data, with variables in columns, observations in rows, and
variable names in the top row
Data Types
Several categorizations are possible: numeric versus categorical, discrete versus continuous,
cross-sectional versus time series; categorical can be nominal or ordinal
Dummy variable
A variable coded 1 or 0: 1 for observations in the category, 0 for observations not in the
category
Binned (or discretized) variable
Numeric variable that has been categorized into discrete categories called bins
, Concatenate
String together two or more pieces of text
Variance
Measure of variability; essentially the average of squared deviations from the mean
Standard Deviation
Measure of variability in same units as observations; square root of variance
Mean absolute Deviation (MAD)
Another measure of variability; average of absolute deviations from the mean
Histogram
Chart of bin counts for a numeric variable; shows shape of the distribution
Box plots
Alternative chart that shows the distribution of a numeric variable
Time Series Graph
Graph showing behavior through time of one or more time series variables
Crosstabs (or contingency table)
Table of counts of joint categories of two categorical variables
Comparison problem
Comparing a numeric variable across two or more subpopulations
Stacked or unstacked data formats
