# Shared Flashcard Set

## Details

Chapter 9 - Descriptive Statistics
Chapter 9 IACA
33
Criminal Justice
Professional
09/05/2014

Term
 Statistics
Definition
 science of collection and organizing data to then draw conclusions based on data
Term
 Types of stats
Definition
 descriptive, multivariate, inferential
Term
 Descriptive statistics
Definition
 summary of large data sets to be put into an easy to read manner
Term
 Multivariate
Definition
 allows comparisons of factors by isolating the effect of one variable from others
Term
 Inferential
Definition
 statements of a population based on a sample
Term
 Levels of measurement
Definition
 nominal, ordinal, interval and ratio
Term
 Characteristics of nominal data
Definition
 lowest level, must be exhaustive, mutually exclusive, only classified one way, provides names or labels (race, gender), can only be one of something
Term
 Characteristics of ordinal data
Definition
 exhaustive, mutually exclusive, exhibits a degree of difference, the degree of difference indicates order/rank, ordering distance has no meaning (good, better, best/agree, disagree, neutral)
Term
 Characteristics of interval
Definition
 assumes all items on scale have equal units of measurement, distance between categories have meaning, logical distances (temp readings, IQ score)
Term
 Characteristics of Ratio
Definition
 has all the characteristics of the other levels plus a true "zero" point. highest level of measurement. (income, weight, time, age)
Term
 Frequency distribution
Definition
 lists the number or frequency of scores/labels for each case
Term
 Range
Definition
 summary statistic with limited information. Highest score-lowest score= range
Term
 Class interval
Definition
 i= range/"n" of desired intervalsexample:i=12-1/4=1111/4= 2.75i=2.75
Term
 Mean
Definition
 average
Term
 Median
Definition
 midpoint/middle score
Term
 Mode
Definition
 most frequent score/label
Term
 Variance
Definition
 sum squared (S^2)deviations of each score from the mean divided by the total number
Term
 Standard deviation
Definition
 average distance each data item is away from the mean of the all the data items. Provides comparison insight between two distributions.
Term
 Skewness
Definition
 the spread of scores weighted to one side of the mean.
Term
 Normal skewness
Definition
 bell shape, the curve doesn't touch the x-axis, curve is symmetrical. Mean, median, mode are equal.
Term
 Positive skewness
Definition
 unimodial scores weighted to the left. Hump to the left, tail to the right. Mode is the largest, followed by the median, and then mean.
Term
 Negative skewness
Definition
 unimodial weighted to the right (hump to the right, tail to the left). Mean largest value, then median, then mode.
Term
 Rates
Definition
 used to standardize measure for comparison between two different items of size. (compare car theft rates between two cities with significant difference in population size).
Term
 Proportions
Definition
 example:60 officers / 15 sgts(15/75)= .20 portion of sgts(60/75) = .80 portion of officers
Term
 Percent changes
Definition
 subtract old value from new value then divide by old value then multiply by 100.
Term
 Correlation analysis
Definition
 measures the relative fit or degree of association between two variable or 3 or more variables to determine the quality of regression line or reliability of prediction.
Term
 Pearson's product moment coefficient
Definition
 =roperates within range 1.0, the closer to one the stronger the value. Zero = no correlation.
Term
 Regression analysis
Definition
 seeks general pattern evident in observation relationships through pattern recognition and placement on a trendline.
Term
 Regression analysis and correlation analysis are similar except regression
Definition
 locates the best line through the points.
Term
 Linear function
Definition
 is one in which data points, x & y coordinates, make more a less straight line.
Term
 Non-linear function
Definition
 is one which the data points, x & y data, make some type of curve shape that can be expressed by an algebraic formula.
Term
 Linear regression
Definition
 to find the best straight line through the points and has the smallest variance, reflecting gaps between the actual placement of the data points on the graph.
Term
 Statistical analysis
Definition
 is multivariate in nature when two or more variables (usually of ratio or interval type) are examined together with the focus on observable relationships or patterns of association, between or among the variables.
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