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, Use only the rare event rule, and make sub...

Use only the rare event rule, and make subjective estimates to determine whether events are likely. For example, if the claim is that a coin favors heads and sample results consis

O-give curves, real time applications on graphical representation of o-give...

real time applications on graphical representation of o-give curves

Regression analysis , The data used is from a statistical software Minitab;...

The data used is from a statistical software Minitab; London.MPJ is the file that consists of 1519 households drawn from 1980 - 1982 British Family Expenditure Surveys. Data that i

Classification of universe, Classification of Universe The universe may...

Classification of Universe The universe may be classified either on the basis of number of units and on the basis   of existence of units as is clear from the following chart :

Evaluate standard deviation, Consider an MBA program as a processing networ...

Consider an MBA program as a processing network where the flow unit consists of a student in the program.  Suppose the organizations that hire and promote MBAs are considered to be

Theoretical yield and actual yield, Write down the symbols and unit for the...

Write down the symbols and unit for the following: mass, molar mass, molar and molarity Write down the relationship between mass and molar mass and show that the units match.

Which average is to be used to describe statistical data?, There ar...

There are situations where none of the three averages is fully satisfactory. For example, if the number of items in a series is very small, none of these av

Circul;atory ststistics Lab, What statistics can be obtained from a circula...

What statistics can be obtained from a circulatory lab?

HLT 362, What is an interaction? Describe an example and identify the varia...

What is an interaction? Describe an example and identify the variables within your population (work, social, academic, etc.) for which you might expect interactions?

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