Standard deviation for grouped data, Applied Statistics

Assignment Help:

Grouped data 

For grouped data, the formula applied is  σ = 1926_standard dviation for grouped data.png

Where f = frequency of the variable, μ= population mean.

Example 17

 

A security analyst studied hundred companies and obtained the following Return on Investment (ROI) data for the year 20x3.

Returns %

0-10

10-20

20-30

30-40

No. of companies

19

32

41

8

We can find how the ROI of the company varies with the mean ROI by calculating the standard deviations for the above data.

The steps involved are:

  • Find mean for grouped data.

  • Find deviations from mean for grouped data.

  • Find squares of the above deviations.

  • Total the squared deviations taking frequency into account.

  •  Calculate square root.

Return on investment

Mid-point

No. of companies

Deviation

%

X

f

fX

   X - μ

 f(X -  μ  )2

0-10

5

19

95

      -13.8

3618.36

10-20

15

32

480

-3.8

462.08

20-30

25

41

1025

6.2

1576.04

30-40

35

8

280

16.2

2099.52

Total

 

100

1880

 

7756.00

Mean

2299_standard dviation for grouped data1.png

= 18.8%.
 

 


Standard Deviation 

=

775_standard dviation for grouped data2.png
  = 309_standard dviation for grouped data3.png =8.81%

Thus, the standard deviation for the return on investment is 8.8%.

In such a calculation, we always assume that all the observations in a class interval are located at the mid-point of the class. For example, the first class interval has mid-point 5 and frequency 19. Hence the assumption is that all the 19 companies have an ROI of exactly 5%.


Related Discussions:- Standard deviation for grouped data

Evaluate the standard deviation, You have an assembly line which produces 1...

You have an assembly line which produces 1L bottles of seltzer with a standard deviation of 0.05L. • Assuming the distribution of volume is normal, what is the chance any single

Descriptive statistics, find the average rate of increase in population whi...

find the average rate of increase in population which in the first decade has increased 20%.in the second 25% and in the third 44%

X-bar charts when the mean and standard deviation not known , Charts when t...

Charts when the Mean and the Standard Deviation are not known We consider the data corresponding to the example of Piston India Limited. Since we do not know population mean a

Explain ridge regression, Using log(x1), log(x2) and log(x3) as the predict...

Using log(x1), log(x2) and log(x3) as the predictors, do pair wise scatterplots of all pairs of variables (including the response) and comment (use the pairs function). Do you thin

Quota sampling, Quota sampling Under this method enumerators shall sele...

Quota sampling Under this method enumerators shall select the respondents in place of those not available, as per the quota fixed according  to guide lines   provided to them.

BIVARIATE FREQUENCY , MARKS IN LAW :10 11 10 11 11 14 12 12 13 10 MARKS IN ...

MARKS IN LAW :10 11 10 11 11 14 12 12 13 10 MARKS IN STATISTICS :20 21 22 21 23 23 22 21 24 23 MARKS IN LAW:13 12 11 12 10 14 14 12 13 10 MARKS IN STATISTICS:24 23 22 23 22 22 24 2

Vital statistics, How vital statistics are affects on our human life

How vital statistics are affects on our human life

Calculate the line of best fit, The manager of Pizza Hut provides a deliver...

The manager of Pizza Hut provides a delivery service for customers who telephone in an order. The manager would like to give callers an idea of the time it will take to deliver an

Simple linear regression, For each of the following situations choose the s...

For each of the following situations choose the statistical model that you find to be the most appropriate. Justify your choice. a) We are interested in assessing the effects of

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd