Diff Two Means
Diff Two Proportions
Odds Ratio
Relative Risk
Chi Square
ANOVA
Correlation
Regression
Logistic Regression
Structural Equation Modeling
Multilevel Analysis
Additional Resources
Sample size determination is an important and often difficult step in planning an empirical study. From a statistical perspective, sample size depends on the following factors: type of analysis to be performed, desired precision of estimates, kind and number of comparisons to be made, number of variables to be examined, and heterogeneity of the population to be sampled. Other important considerations include feasibility, such as ethical limitations on access to a population of interest and the availability of time and money. The primary assumption of this book is that, within the context of ethical and practical limitations, efforts to obtain samples of appropriate size and quality remain an important and viable component of social science research.
This text describes the following available approaches for estimating sample size in social work research and discusses their strengths and weaknesses: (1) power analysis, (2) confidence intervals, (3) computer-intensive strategies, and (4) ethical and cost considerations. In addition, strategies for mitigating pressures to increase sample size, such as emphasis on model parsimony (e.g., fewer dependent and independent variables), simpler study designs, an emphasis on replication, and careful planning of analyses are discussed. This text covers sample-size determination for advanced and emerging statistical strategies, such as structural equation modeling, multilevel analysis, repeated measures MANOVA, and repeated measures ANOVA which are not discussed in other texts including Cohen (1988). This book can serve either as a supplemental text for an introductory course or as a core text for a more advanced course.
Calculate sample size for a study comparing means (p. 147)
Compute CI of a sum, difference, quotient, or product (p. 43)
Difference between Two Proportions
Difference Between Two Proportions-Power and Sample Size (p. 21)
Calculator for the confidence interval for the difference between two independent proportions (p. 45)
Calculate for confidence interval around an odds ratio (p. 46)
Calculator for confidence intervals for odds ratio unmatched case control study
Calculate the confidence interval for relative risk (p. 147)
Calculate confidence intervals around chi square (p. 46)
ANOVA-Power and Sample Size (p. 24)
PSY calculate confidence intervals around contrasts (p. 49)
Power Analysis for ANOVA Designs
Calculate confidence intervals around rho (p. 49)
Calculate the 99%, 95%,and 90% confidence intervals for a regression coefficient (p. 51)
Calculate the 99%, 95%,and 90% confidence intervals for R-squared (p. 51)
Calculate an adjusted R-squared (p. 51)
R2 calculates confidence intervals for R-squared (p. 51)
R2 manual [pdf] (p. 51)
Calculator the effect size for multiple regression (f2), given a value of R2 (p. 146)
Logistic Regression with Binary Covariate(s)-Power and Sample Size (p. 31)
Logistic Regression with Exposure Measurement Error (p. 32)
NIESEM is a program for calculating user-defined confidence intervals around noncentral fit indices (p. 34)
Optimal Design Software-optimal design for longitudinal and multilevel research (p. 37)
Optimal Design Software Manual (p. 37)
Probability Distributions and Related Distributions
Calculator for confidence intervals for odds ratio unmatched case control study
Comparing Single Proportion to Known Population
Computer Software for Power Analysis in Covariance Structure Modeling
Distribution Density Calculators, Plotters and RNG's
Calculate sample size necessary to detect the difference between two proportions
Various web-based statistical tools
Free Web Development Resources
Free Web Development Resources - Overview of the Web Color Model
GraphPad QuickCalcs Confidence interval of a SD
Interactive Statistical Calculation Pages
Interactive Statistical Calculation Pages2
Interactive Statistical Calculation Pages
JavaStat -- Retrospective Power Calculations
Martindale's Calculators On-Line Center
Martindale's Calculators On-Line Center Statistics - Courses
Noncentral Student CDF Calculator
Power Analysis for ANOVA Designs
Power Slates in HyperCourseware
Power and Sample Size Calculation for Logistic Regression with Binary Covariate(s)
Sample Size Calculations for Logistic Regression with Exposure Measurement Error
Sample Size Calculator by Raosoft, Inc.
Sample Size for Controlled Trials
The Ideas Behind Statistical Power
Java applet that demonstrates features of ANOVA
Victor Bissonnette's Home Page (useful statistical tables and more)
Data Generator is a free, open source script written in JavaScript, PHP and MySQL that lets you generatecustom data in a variety of formats.
Calculate combinations and permutations
Raynald's SPSS Tools contains 675 plus examples of syntax, macros, and scripts
Easy Calculation.com-Online Statistics Calculators for mean, median, mode, standard deviation, geometric mean, grouped data arithmetic mean, class interval arithmetic mean, root mean square, correlation coefficient, regression, harmonic mean.
last updated: 03/07/2008