# Shared Flashcard Set

## Details

Econometrics Chapter 7
Econometrics Chapter 7
39
Economics
01/18/2013

Term
 arithmetic mean
Definition
 a measure of central tendency in a data set that is computed by adding together all te individual observations and dividing the sum so obtained by the number of observations; as a result, the sum of deviations of all observations from this mean equal zero
Term
 bimodal frequency distribution
Definition
 a frequency distribution in which two different values occur with the highest frequency or almost that
Term
 Chebyshev's theorem
Definition
 regardless of the shape of a population's frequency distribution, the proportion of observations falling wihtin k standard deviations of the mean is at least 1-(1/k^2), give that k equal 1 or more
Term
 coefficient of kurrtosis
Definition
 a measure of shape that classifies frequency curves as platykurtic,mesokurtic, or leptokurtic
Term
 coefficient of variation
Definition
 a measure of relative dispersion, equal to the ratio of the standard deviation to the arithmetic mean
Term
 control charts
Definition
 graphical devices that highlight the average performance of data series and the dispersion around this average so the average and dispersion of the past become standards for controlling performance in the present
Term
 deciles
Definition
 values in a data set that divide the array of all observations into ten parts, each of which contains0.10 (or 10 percent) of the observed values
Term
 empirical rule
Definition
 whenever a statistical population can be described, at least roughly, by the perfectly symmetrical , bell-shaped normal curve, we can estimate the percentages of all population values that lie within specified numbers of standard deviations from the mean: approximately 68 percent of all values lie within 1 standard deviation from the mean about 95 percent lie within 2 standard deviations from the mean; and practically all values lie within 3 standard deviations from the mean
Term
 first quartile
Definition
 the 0.25 fractile (or 25th percentile) in a data set, such that a quarter (or 25 percent) of all values are smaller than or at most equal to it
Term
 fractile
Definition
 any value in a data set such that a specified proportion of all values is smaller than or at most equal to it
Term
 interfractile ranges
Definition
 distance measures of dispersion, equal to differences between two fractiles in a data set
Term
 interquartile range or H-shaped
Definition
 a distance measure of dispersion; the difference between the third and first quartiles, containing the middle 50 percent of all values observed
Term
 kurtosis
Definition
 a measure of shape, noting a frequency curve's degree of peakedness
Term
 mean absolute deviation
Definition
 an average measure of dispersion in a data set; it equals the arithmetic mean of all the absolute differences between each individual observation and the data set's mean (or, sometimes, median)
Term
 measures of central tendency or measures of location
Definition
 values which observations tend to cluster and that describe the location of what in some sense might be called the "center" of a data set
Term
 measures of dispersion or measures of variability
Definition
 numbers that indicate the spread or scatter of observations; they show the extent to which individual values in a data set differ from one another and, hence, differ from their central location
Term
 measure of shape
Definition
 numbers that indicate either the degree of asymmetry or the degree of peakedness in a frequency distribution
Term
 median
Definition
 a measure of central tendency that divides and ordered array of data into two halves; if the data are arranged in ascending order from smallest ot largest, all the observations below the median are smaller than or equal to it, while all the observations above the median are equal to it or larger. If the total number of observations is odd, the media is the middle observation in the ordered array; if the total number of observations is even, the median is the average of the two middle values
Term
 median class
Definition
 the class among grouped data that contains the median
Term
 midrange
Definition
 the sum of data set's minimum plus maximum values, divided by 2
Term
 modal class
Definition
 the class among grouped data that contains the mode
Term
 mode
Definition
 a measure of central tendency that is the most frequently occurring value in a data set
Term
 multimodal frequency distribution
Definition
 a frequency distribution in which two or more different values occur with the highest frequency or almost that
Term
 normal curve
Definition
 a frequency curve that has the characteristics (1-3) of the normal frequency distribution
Term
 normal frequency distribution
Definition
 a population whose relative frequency density is characterized by three features (1) it is single-peaked above the population's mean,median,and mode, which coincide, (2) it is perfectly symmetric about this central value, and (3) it has tails extending indefinitely in both directions from the center, approaching, but never touch, the horizontal axis
Term
 parameter
Definition
 a summary measure based on population data
Term
 Pearson's coefficient of skewness
Definition
 a measure of shape that focuses on the difference between mode and the mean and then realtes it to the standard deviation
Term
 percentile
Definition
 any value in data set such that a specified percentage of all values is smaller than or at most equal to it
Term
 proportion
Definition
 a number that describes the frequency of observations in a particular category as a fraction of all observations made
Term
 quartiles
Definition
 values in a data set that divide the array of all observations into four quarters, each of which contains 0.25 (or 25 percent) of the observed values
Term
 range
Definition
 a distance measure of dispersion; the difference between the largest and smallest observation in a set of ungrouped data or between the upper limit of the largest class and the lower limit f the smallest class for grouped data
Term
 second quartile
Definition
 the 0.50 fractile (or 50th percentile) in a data set, such that half (or 50 percent) of all values are smaller than or at most equal to it
Term
 skewness
Definition
 a measure of shape,noting a frequency distribution's degree of distortion from horizontal symmetry
Term
 standard deviation
Definition
 an average deviation measure of dispersion in a data set; equal to the positive square root of the variance
Term
 statistic
Definition
 a summary measure based on sample data
Term
 third quartile
Definition
 the .75 fractile (or 75th percentile) in a data set, such that three quarters (or 75 percent) of all alues are smaller than or at most equal to it
Term
 trimmed mean
Definition
 the arithmetic mean of a data set after an equal percentage of smallest and largest observations have been deleted from its ordered array
Term
 variance
Definition
 an average deviation measure of dispersion in a data set; for population, it is constructed by taking the difference between each observed value and the population mean, squaring each of these deviations, and then finding the arithmetic mean of the squared values; for a sample, a roughly analogous expression is constructed with the help of the sample mean
Term
 weighted mean
Definition
 a measure of central tendency that gives unequal weights to different observations according to their unequal relative importance this special type of arithmetic mean equals the sum of the products of observed values and their respectie weight, divided by the sum of the weights
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