## Quiz 9 :

Determining Sample Size and the Sample Plan

Answer:

The formula for estimating percentage in population is given below:

The calculated sample size is represented as n.

Standard value chosen with the level of confidence is represented as z.

Estimated percentage in the population is represented as p.

100% - p is represented as q.

Acceptable error is represented as e.

Level of confidence is represented as z in the formula.

The level of confidence is the confidence level that refers to how confident the marketers are if different survey is conducted the next day with the population and it results in the same sample size.

• For 95% of confidence, the value of z is 1.96.

• Commonly used values for z is 1.96, which means if the survey is to be conducted for 100 times then for 95 times the value of sample finding will fall within the predetermined level of accuracy.

• This leads to confidence in the reliability of sample finding.

Thus, the concept of level of confidence is expressed in the percentage value of the confidence level.

Answer:

Sample frame is comprised of the master list of members or things included in a defined population. Sample frame is updated for each new entry in population.

Sample frame error comprises the difference between sample frame list and the actual existence of a particular population. It shows the misrepresentation of population in the sample frame list.

Errors found in the household listing of a telephone book are listed below:

• Missing numbers.

• Typing errors.

• Absence of new numbers obtained after publishing the directory.

• Disconnected telephone numbers.

• Telephone device failure.

• Numbers which have unpaid bills.

These errors show the misrepresentation of household listing present in a telephone book.