Unit 3 Discussion Board
A sample is a fraction of a population. From the sample we determine a sample size, which is the number of observations in the sample. Researchers consider sample size determination an integral step of a study. One thing that will help determine a sample size is the amount of error and population the researcher is willing to tolerate (Krejcie& Morgan, 1970).
Some other factors that researchers considers when determining sample size are the analysis that will be performed, the parameters of the population that is to estimated, what is already known, the variability of the population, number of variables that will be studied, and the precision of what we want our estimates to be (Dattalo, 2008). Researchers must also keep in mind the cost of taking samples, availability and feasibility.
Sample size calculators allows for the calculation of a confidence interval, standard error, relative standard error, and the responding sample size for a proportionate estimate (Sample Size Calculator, n.d.). Using a sample size calculator will allow you to determine the number of observations that will be need to get the results desired to reflect the target population.
The two calculators that I chose were by National Statistical Service and Bold Educational Software (Dusick, 2011). The population that I chose was 1000, the confidence level was 95%, and the confidence interval was 5%. They both produced the same sample size, however, the calculator from National Statistical Service was better for me. It had instructions and example on how to fill in the calculator and provided the elative standard error and the standard error (Sample Size Calculator, n.d.). Overall it was easier to operate. The Bold calculator only provided the sample size.
Dattalo, P. (2008). Determining Sample Size: Balancing Power, Precision, and Practicality.Oxford University Press, USA.
Dusick, D. (2011). Sample Size Calculator.In Bold Educational Software. Retrieved from http://bold-ed.com/calculator.htm#calculator
Krejcie, R. V., & Morgan, D. W. (1970). Determining sample size for research activities. Educational and Psychological Measurement, 30, 607-610.
Sample Size Calculator. (n.d.). In National Statistical Service.Retrieved from http://www.nss.gov.au/nss/home.NSF/pages/Sample+Size+Calculator+Description?OpenDocument