As a public service of Creative Research Systems there are several statistical research aids available.

Sample size calculator: To know about confidence interval and confidence level http://www.surveysystem.com/sscalc.htm

Sample size formula:  The formulas used in our Sample Size Calculator http://www.surveysystem.com/sample-size-formula.htm

Significance:  It is an article. In first part it simplifies the concept of statistical significance to non-technical readers enabling them to use the concept to help make decisions based on their data. The second part provides a fuller discussion of the exact meaning of statistical significance numbers to more technical readers. http://www.surveysystem.com/signif.htm

Survey Design: This is a chapter from The Survey System's Tutorial, revised May, 2008. This chapter is intended primarily for those who are new to survey research. It discusses options and provides suggestions on how to design and conduct a successful survey project. It does not provide instruction on using specific parts of The Survey System, although it mentions parts of the program that can help you with certain tasks. http://www.surveysystem.com/sdesign.htm

Correlation: In this section you it briefly discusses about techniques determining correlation, rating scales and correlation coefficient.  http://www.surveysystem.com/correlation.htm

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The Matlab Health and Demographic Surveillance System of ICDDR,B is the oldest longitudinal demographic surveillance system in the developing world. The Matlab Demographic Workbook is an easy to use, interactive Excel file that houses data for all demographic events occurring in Matlab, Bangladesh since 1983. The information is indexed by ICDDR,B area and Government services area, year, sex and age group. Users can enquire about any of the demographic events by a specific year or assess trends over time. The workbook, which accommodates data to 2020, will be updated once annually with the most recent demographic events. In addition, the tool enables monitoring of the progress in Matlab towards MDG 4 i.e. reducing child mortality. During 2007, data for 1974 to 1982 will be added to the workbook, thereby facilitating access to longitudinal data from 1974 to the present. To visit the site>> http://www.icddrb.org/activity/index.jsp?activityObjectID=2878

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This is a page from personal website of Dr. John Eng of The Russell H. Morgan Department of Radiology and Radiological Science Johns Hopkins University, Baltimore, Maryland, USA. This page calculates the sample size for four simple study designs. The equations are more fully discussed in Ref. 1. To estimate a sample size, identify the equation appropriate to your study design. Enter values for the parameters under "Input Values" and click the corresponding "Calculate" button. To visit this page>> http://www.rad.jhmi.edu/jeng/javarad/samplesize/#details

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