# NCERT Class 12 Practical Geography Chapter 2 Data Processing YouTube Lecture Handouts Part 3

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## Range

40, 42, 45, 48, 50, 52, 55, 58,60, 100

• Range (R) is the difference between maximum and minimum values in a series of distribution. This way it simply represents the distance from the smallest to the largest score in a series. It can also be defined as the highest score minus the lowest score
• (highest – lowest)
• If we eliminate the 10th case, R becomes 20 (60 – 40) . The elimination of one score has reduced the R to just one-third. It is obvious that the difficulty with R as a measure of variability is that its value is wholly dependent upon the two extreme scores.

## Mean Deviation

• Mean Deviation gives equal importance to all deviations about mean or about any other point (median)
• Standard deviation gives greater weightage to higher deviations about mean

### Mean Deviation (Ungrouped Data)

 50 40 15 15

### Finding Mean First

 Class Mid-point Units(f) 0 - 10 2 10 - 20 4 20 - 30 3 30 - 40 1 40 - 50 5

### Mean Deviation (Grouped Data)

 Class Mid-point Units(f) 0 - 10 2 10 - 20 4 20 - 30 3 30 - 40 1 40 - 50 5

## Standard Deviation of Ungrouped Data Long & Short Method

### Standard Deviation (Ungrouped Data)

1, 3,5, 7,9

 1 3 5 7 9
• When the observations for different places or periods are expressed in different units of measurement and are to be compared, the coefficient of variation (CV) proves very useful. CV expresses the standard deviation as a percentage of the mean
• Coefficient of Variation for grouped data can also be calculated using the same formula
• Standard Deviation is the positive square root of the average of squares of deviation about mean. Here greater weightage is given to higher deviation along mean.

### Standard Deviation (Ungrouped Data)

1, 3,5, 7,9

 1 3 5 7 9
• When the observations for different places or periods are expressed in different units of measurement and are to be compared, the coefficient of variation (CV) proves very useful. CV expresses the standard deviation as a percentage of the mean
• Coefficient of Variation for grouped data can also be calculated using the same formula
• Standard Deviation is the positive square root of the average of squares of deviation about mean. Here greater weightage is given to higher deviation along mean.

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