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

What are the charateristics of a population for which, what are characteris...

what are characteristics of a population for which it would be appropiate to use mean/median/mode

Probability, There are 15 types of ice cream: A,B,C,D,E,F,G,H,I,J,K,L,M,N, ...

There are 15 types of ice cream: A,B,C,D,E,F,G,H,I,J,K,L,M,N, and O. How many combinations are there to sample 5 flavors if you sample 1 flavor 4 times? How many combinations are t

Type i and ii errors, TYPE I AND II Errors If a statistical hypothesis ...

TYPE I AND II Errors If a statistical hypothesis is tested, we may get the following four possible cases: The null hypothesis is true and it is accepted; The

Types of cost-reimbursable contracts, Types of cost-reimbursable contracts ...

Types of cost-reimbursable contracts are:   Cost Plus Fixed Fee contract (CPPF): Compensation is based on a fixed sum independent of the final project cost. The customer a

Coefficient of variation, Coefficient of Variation The standard dev...

Coefficient of Variation The standard deviation discussed above is an absolute measure of dispersion. The corresponding relative measure is known as the coefficient of vari

Hypothesistesting, Apl.send me nots on hypothesis testing sk question #Mi...

Apl.send me nots on hypothesis testing sk question #Minimum 100 words accepted#

Distrbution., The score distribution shown in the table is for all students...

The score distribution shown in the table is for all students who took a yearly AP statistical exam. An AP statistics teacher had 59 students preparing to take the AP exam. Though

Determine the matrix of the transformation, Consider the linear transformat...

Consider the linear transformation (a) Find the image of (3 , -2 , 2) under T. (b) Does the vector (5, 3) belong to the range of T? (c) Determine the matrix of the transf

Probability, 2.1 Modern hotels and certain establishments make use of an el...

2.1 Modern hotels and certain establishments make use of an electronic door lock system. To open a door an electronic card is inserted into a slot. A green light indicates that the

Multivariate statistical methods, As one of the oldest multivariate stati...

As one of the oldest multivariate statistical methods of data reduction, Principal Component Analysis (PCA)simplifies a dataset by producing a small number of derived

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