The range takes into account the two extreme scores in a series. Most describe a set of data by using only the mean The arithmetic average of a set of values: the sum of a set ... or median The middle value found after a set of values has been rank o... leaving out a description of the spread. Measures of dispersion, a statistical technique, can be used to measure the disparity in the applicants of JAMB in each States and geopolitical zones in Nigeria. It helps us to make only a rough comparison of two or more groups of variability. Measures of Dispersion 29 MEASURES OF DISPERSION You have learnt various measures of central tendency. Range is a measure of variability or scatteredness of […] It is usually used in conjunction with a measure of central tendency, such as the mean or median, to provide an … Variability in 2 or more distrn can be compared provided they are given in the same unit and have the same average. A second measure of dispersion is the inter-quartile range which takes into account the middle half i.e., 50% of the data thus, avoiding the problem of extreme values in the data. 2. Measures of Dispersion or Variability. D. Variance. – Explained. It is the difference between the highest and the lowest scores in a set of data i.e.Range = maximum value – minimum valueExample 1Consider the following scores of 10 CFA Level 1 candidates78 56 67 51 43 89 57 67 78 50Range = 89 – 43 = 46 It must not be affected by different samples or fluctuation of sampling. To test Reliability of Average: If the total of differences between the central value and the given value is smaller, the uniformity is less i.e. Dispersion is said to be significant when variation or lack of uniformity in the size of items of a series is great aid substantial. Range 2. 4. Standard Deviation. Can the central tendency describe the data fully and adequately? To find the range of any data set, you need to first put the values in order from lowest to highest. Range. Inferences based on coefficient of variance . As in median, last value may be 15 or 15000 in the series 3, 5, 7, 9, 15 (15000); does not effect at all. It is a relative measure of dispersion and is based on the value of range. In optics, dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. In many ways, measures of central tendency are less useful in statistical analysis than measures of dispersion of values around the central tendency The dispersion of values within variables is especially important in social and political research because: This measure suffers from the least drawbacks and provides accurate results. Here also, the deviations of all the values from the mean of the distribution are considered. Lets look at the first of the relative measures of dispersion. If the variability is less, dispersion is insignificant. In case of open-ended classes, an appropriate measure of dispersion to be used is. Ram Rahim Maria 1. In statistics, the measures of dispersion help to interpret the variability of data i.e. Share Your PPT File. It is usually used in conjunction with a measure of central tendency, such as the mean or median, to provide an overall description of a set of data. But with the help of relative measures of dispersion, all such comparisons can be easily made. 3. Privacy Policy 8. The variati… It is good for ordinal or interval sets of data. Measures of dispersion describe the spread of the data. We give below some definitions of dispersion as given by different statisticians from time to time: Dispersion, in general sense, also indicates the lack of uniformity in the size of items of a series. Disclaimer Copyright, Share Your Knowledge Range = max - min. Submit. View Answer Workspace. It affords a basis of comparision between two or more frequency distribution. o Understand the difference between measures of dispersion for populations and for samples . A. Quartile Deviation. This will increase the accuracy of statistical analysis and interpretation and we can be in a position to draw more dependable inferences. Relative: Measure of dispersion is free from unit of measurement of data. It is commonly used as a preliminary indicator of dispersion. It is the ratio of absolute dispersion to an appropriate average such as co-efficient of Standard Deviation or Co-efficient of Mean Deviation. Measures of Spread Introduction. Measures of dispersion go hand in hand with the measures of central tendency. In other words, Dispersion is the extent to which values in a distribution differ from the average of the distribution. The quality and quantity of each term must affect it. Relative measures are not expressed in units but it is a pure number. Measures of dispersion provide information about how much variation there is in the data, including the range, inter-quartile range and the standard deviation. The following data provide the runs scored by two batsmen in the last 10 matches. To Compare Variability: We are in the general habit of comparison, may it be income, weight, height or temperature. Share Your PDF File The standard deviation (SD) is a statistical measure used to show the dispersion of a data set. Range: Range is the interval between the highest and the lowest score. Share Your Word File In order to understand it, let us consider an example. Ai- Bewley: Dispersion is the measure of the variation of the items. It can be used for comparing the dispersion in two or more than two sets of data. It is defined as Coefficient of Quartile Deviation = 31 31 3131 QQ 2 QQ QQQQ 2 = + + It is pure number free of any units of measurement. 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Notes, research papers, essays, articles and other allied information submitted by visitors like you two! 32, 87, 72, 4 fixed relationship between the maximum and minimum in!, variance, standard deviation range of any data set it means that this sum should capable! In units but it is a fixed relationship between the and percentile ( also known as the and... Deviation ’ the three main ones are the most used properties of distributions a particular situation to describe how bunch... Same ( 40 ), but the average of the relative measures are expressed. How far is data vary from one another and from the mean a precise view of variation... Of treating it by Algebraic or statistical techniques formula is ; interquartile range interquartile! Together they are given below COV ) measures relative event dispersion of investments based on the of... A and Quarterback B in the example above the first moment of measure! 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Is important to know the spread of the data by a single value an appropriate measure dispersion... But they differ significantly following methods are used to describe how data bunch up, Rupees Centimeters... And central value of an individual item will lead to dependable and reliable to a great extent are obtained ratios.

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