A. A Community Survey provides data every year about communities in the United S

Question

A. A Community Survey provides data every year about communities in the United States. Addresses are randomly selected, and respondents are required to supply answers to a series of questions. Is the Community Survey based on a sample or a population? (State only one answer)

B. A random sample of 300 full-time employees is selected from a company list containing the names of all 5,000 full-time employees in order to evaluate job satisfaction. Give an example of a possible sampling error that may lead to biasedness in the results?

C. Clearly state the difference (in two sentences/definitions) between the concepts “mutually exclusive” and “independent”.

Explanation / Answer

A.

A Community Survey provides data every year and addresses are randomly selected, so Community Survey based on a sample.

B.

THere are many types of sampling error .
Here sample os size 300 are selected randomly from the 5000 full- time employees . There are variation in the salaries of the employees. So there may be chances of over representation and under representation of the groups based
on salaries and so that the sampling error is taken the part in the survey.

   Also there are male and female employees in the company and also there are chances of over representation and under representation on the basis of gender.
So we need to make strata based on the attribute as level of salaries, or gender to minimises the sampling error.

C.

Mutually Exclusive Events:

There are no common elements between events, such events khmown as Mutually Exclusive Events.

If happening of any one of them precludes the happening of all the others. that is if no two or more of them can happen simultaneously in the same trial.

Suppose we have two events mutually exclusive iff: P(AB)=0, i.e. AB=

Independent Events:

Happening or non-happanening of an events is not affected by the supplementary knowledge concerning the occurrence of any number of the remaning events.

If we have two events independent iff: P(AB)=P(A)P(B)

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