SAMPSIZE

This program calculates N, the minimum  number of samples (or replicates) necessary to obtain a desired confidence level. The methods are outlined in Quantitative Methods in Aquatic Ecology by M.C. Newman pp 42-45.
An initial estimate is made using a z statistic. This estimate of N is then used to generate better estimates using two methods:
1. First the number of degrees of freedom (df) is obtained from the initial estimate of N. Then N is recalculated using the t statistic. This step is repeated until two successive estimates of N are equal.
2. An improved value of N is obtained from Table 4 in based on an assurance (tolerance) level.

You will be prompted for the following:
! Desired type of calculation (number of samples or number of replicates)
! Acceptable confidence level
! Assurance level
! Maximum acceptable relative error
! Whether or not the population variance is small relative to the population size
! Estimated coefficient of variation (and, if applicable, population size)

To work through  Example 8 on page 44 of the text, give the following responses at the prompts:


Prompt

CHOOSE DESIRED TYPE OF CALCULATION ...

CHOOSE A CONFIDENCE LEVEL ...

CHOOSE AN ASSURANCE LEVEL ...

ENTER THE MAXIMUM ACCEPTABLE RELATIVE ERROR ...

IS THE POPULATION VARIANCE SMALL RELATIVE TO THE POPULATION SIZE?

ENTER THE ESTIMATED C.V ....


Response

1

1

1

.25


T

.47