ISS (Statistical Services) Statistics Paper III: Questions 24 - 31 of 109

Procedure of drawing Simple random sampling without replacement (SRSWOR):

In SSWOR once an element is selected as a sample unit, it will not be replaced in the population pool. The selected sample units are distinct.

A sample of size is collected without replacement from the population of size . First member is chosen at random

Two Stage Sampling:

All elements are surveyed in cluster sampling and efficiency in cluster sampling depends on size of the cluster. As the size increases, the efficiency decreases.

Rather than enumerating all the sampling units in the selected clusters, one can get better and more efficient estimators by resorting to sub sampling within the clu

Multicollinearity: Implies predictors that are correlated with other predictors in the model. Here two or more predictor variables in a multiple regression model are highly correlated and implies that one can be linearly predicted from the others with a substantial degree of accuracy.

Causes of multicollinearity:

• Inaccurate use of dummy vari

Precautions to be taken for planning sample survey:

1. Objectives of the survey: The first step is to define clearly the objective of the survey. The objective should be kept easy so that the people working for the survey easily understand it. The hypothesis being tested and the outcomes that will be used to study the hypothesis should be clear.

Second order autoregressive series:

Sometimes, the values of a time series data are highly correlated with the values that precede and succeed them. i. e. , The value of a time series at any time “t” may depend upon its own value at times t-1, t-2, …, t-k, the relationship being linear.

In such cases an auto-regression model is used for forecast