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# Median2

## on Feb 02, 2010

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## Median2Presentation Transcript

• Median Princy Thomas
• Median
• The median is the middle of a distribution: half the scores are above the median and half are below the median. The median is less sensitive to extreme scores than the mean and this makes it a better measure than the mean for highly skewed distributions. The median income is usually more informative than the mean income, of central tendency
• Summary Measures Central Tendency Mean Median Mode Quartile Geometric Mean Summary Measures Variation Variance Standard Deviation Coefficient of Variation Range
• Median
• Robust Measure of Central Tendency
• Not Affected by Extreme Values
• In an Ordered Array, the Median is the ‘Middle’ Number
• If n or N is odd, the median is the middle number
• If n or N is even, the median is the average of the 2 middle numbers
0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 12 14 Median = 5 Median = 5
• Individual series or ungrouped data
• First arrange the values in increasing order.
• Median = size of n+1 th item 2
• Question no 1
• Find the median from the following data
• 4,45,60,20,83,19,26,11,27,12,52
• Question No2
• Find the median from the following data
• 35,23,45,50,80,61,92,40,52,61
• Median 2 Discrete series
• Discrete Series
• Find the cumulative frequency
• Then calculate the measure of (N+1)/2 th item .
• The value we can easily locate with the help of the table. Here the variable is an integral value.
• Question No 1
• Find the median from the following data
• Wages 10 12 15 18 20 25 30
• .F 3 5 8 12 13 8 7
• Note 1
• if the series is is an inclusive one we should change the inclusive series into exclusive one.
• For eg. 11-15 16-20
• 10.5-15.5 15.5-20.5
• Note 2
• If the classes are not equal, make the classes equal
• Wrong Form Right Method
• 10-15 10-20
• 15-17.5 20-30
• 17.5-20 30-40
• 20-30
• 30-35
• 35-37.5
• 37.5-40
• Continuous Frequency distribution
• Prepare less than cumulative frequency
• Find N/2
• See cumulative frequency just greater than N/2
• The corresponding class contains the median value and is called the median class
• The formula for median Class
• c.f- is the cumulative frequency of the class just preceding the median class
• C-magnitude of the class interval
• f- frequency of the median class
• Note 3
• Median is the best suitable measure for open ended classes
• Question 1
• Compute the median
• Class 0-10 10-20 20-30 30-40 40-50 50-60 60-70
• Freq 8 12 20 23 18 7 2
• Question
• Draw a less than cumulative frequency curve for the following data and find the median
10 13 17 20 20 30 65 35 28 12 No of Workers 900-1000 800-900 700-800 600-700 500-600 400-500 300-400 200-300 100-200 0-100 Monthly income