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

Statistical procedures - estimation of a mean, Old Faithful Geyser in Yello...

Old Faithful Geyser in Yellowstone National Park derives its names and fame from the regularity (and beauty) of its eruptions. Rangers usually post the predicted times of eruptions

Characteristics of index number, Characteristics of Index Number  On th...

Characteristics of Index Number  On the analysis of various definitions of index number the following may be its characteristics: 1.      Expressed in Number : Index number

Professional Counselor, A researcher hypothesized that the pulse rates of ...

A researcher hypothesized that the pulse rates of long-distance athletes differ from those of other athletes. He believed that the runners’ pulses would be slower. He obtained a ra

Case # 2 , Case Problem: A Bipartisan Agenda for Change In a study conducte...

Case Problem: A Bipartisan Agenda for Change In a study conducted by Zogby International, more than 700 New Yorkers were polled to determine whether the New York state government w

Write out the estimator of the linear combination, Now, let's look at a dif...

Now, let's look at a different linear combination. Suppose we are interested n comparing the average mean log income for no college education ( 16). 1. Write out the linear com

Simple regression analysis, Construct your initial multivariate model by se...

Construct your initial multivariate model by selecting a dependent variable Y and two independent variables X. Clearly define what each variable represents and how this relates t

Probability distribution and sampling distribution , a 100 squash balls are...

a 100 squash balls are bounce from height of 100 inches with average height 30 inch with standard deviation 3/4 inch. a ball is fast if bounce above 32 inch. what is chance of gett

Ogive graphs, how many types of ogive are there

how many types of ogive are there

Central tendency and dispersion in statistics, Central Tendency and Dispers...

Central Tendency and Dispersion in Statistics: Write a note on the following : i)    What is the importance of Measures Of Central Tendency and Dispersion in Statistics ?

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