Sampling, Applied Statistics

Sampling

Population is a collection of all the data points being studied. For example, if we are studying the annual incomes of all the people in India, then the population under study would consist of data points representing the incomes of each and every person in India.

Sample is a part of a population.

In the above example the following would be some possible samples:

  1. The annual incomes of all the people in Mumbai.

  2. The annual incomes of all the people in India over forty years of age.

  3. Your own annual income (assuming you are in India).

  4. The annual incomes of the first hundred people mentioned in your telephone directory.

Samples, being smaller in size than their population, are easier to study. Hence, if we want to draw some conclusions about a population, we can do so by studying a suitable sample of the population.

Example 

In which of the following cases do the samples appear to be suitable for arriving at conclusions about the corresponding populations?

1.

Population

:

Annual income of every person in India.

 

Sample

:

Annual income of randomly selected persons in Mumbai.

 

Answer

:

Not a representative sample because it is Mumbai.

2.

Population

:

Likely customers for an exclusive credit card scheme.

 

Sample

:

Regular commuters on public transport buses.

 

Answer

:

May not be a representative sample because regular commuters on public transport buses may not be in the income range high enough to support an exclusive credit card holding.

The following notations are used to denote population parameters and sample statistics.

 

Population

Sample

Characteristic

Parameter

Statistic

Size

Mean

Standard Deviation

Proportion

N

  μ

  σ

p

n

  1126_computation of covariance ungrouped data2.png

S

  388_sampling.png

Posted Date: 9/15/2012 2:53:04 AM | Location : United States







Related Discussions:- Sampling, Assignment Help, Ask Question on Sampling, Get Answer, Expert's Help, Sampling Discussions

Write discussion on Sampling
Your posts are moderated
Related Questions
Q. Compute the output of correlation? The following figure shows (a) a 3-bit image of size 5-by-5 image in the square, with x and y coordinates specified, (b) a Laplacian

You want to know the thoughts of air travelers in fields such as tickets, comffort, safety, securuty, services and economic growth. You are given a database and 20 questions to ask

Chi Square Test as a Distributional Goodness of Fit In day-to-day decision making managers often come across situations wherein they are in a state of dilemma about the applica

Regression line drawn as Y=C+1075x, when x was 2, and y was 239, given that y intercept was 11. calculate the residual

Each weekend, Derek either reads a book (B), goes to the cinema (C), visits his local museum (M), or plays squash (S). If he reads a book one weekend, then he will take part in one

A salesperson visits from house to house to sell her knives. The probability that she makes a sale at a random house is .3. Given that she makes a sale, the sale is worth $100 with

give me question on mean is the aimplest average to understand and easy to compute

#questionMaximize Z= 3x1 + 2X2 Subject to the constraints: X1+ X2 = 4 X1 - X2 = 2 X1, X2 = 0..

Disadvantages The value of mode cannot always be determined. In some cases we may have a bimodal series. It is not capable of algebraic manipulations. For example, from t

In a three-cornered paint ball duel, A, B, and C successively take shots at each other until only one of them remains paint free. Once hit, a player is out of the game and gets no