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

#vital statistics, # I have to make assignment on vital statistics so kindl...

# I have to make assignment on vital statistics so kindly guide me how to make and get good marks

Statistical inquiry, Main stages of Statistical Inquiry The following a...

Main stages of Statistical Inquiry The following are the various stages of a statistical inquiry (1)   Planning the Inquiry: First of all we have to assess the problem und

Heteroskedastic-consistent standard errors, The following table shows the r...

The following table shows the results of fitting a linear regression model of starting annual salaries on a constant, GPA (4 point scale), and a variable (Metrics =1) indicating wh

student is chosen randomly, In a management class of 100 childerns' 3 lang...

In a management class of 100 childerns' 3 languages are offered as an additional subject viz. Hindi, English and Kannada. There are 28 childrens taking Hindi, 26 taking Hindi and 1

Primary and secondary data, Primary and Secondary Data: Primary Data: ...

Primary and Secondary Data: Primary Data: These data are those are collected for the first time. Thus primary data are original in character and gathered   by actual observat

Simulation, Simulation When decisions are to be taken under conditions ...

Simulation When decisions are to be taken under conditions of uncertainty, simulation can be used. Simulation as a quantitative method requires the setting up of a mathematical

Number of principal components, While there are p original variables the n...

While there are p original variables the number of principal components is m such that m

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

Advantages of median, Advantages It is especially useful in c...

Advantages It is especially useful in case of open-end classes since only the position and not the values of items must be known. The median is also recommended if th

Calculate the standard deviation, Zinc is a trace element and it is importa...

Zinc is a trace element and it is important in wound healing, building up the immune system and DNA synthesis. The data in Table 1 represents the zinc intake (in milligrams) for a

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