IBM SPSS SamplePower

Get the right sample size the first time

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  • Overview
  • Features and Benefits
  • System Requirements

Whether you’re an advanced or beginning statistician or researcher, you’ll easily identify the appropriate sample size – every time – for any research criteria.

If your sample size is too small, you could miss important research findings. If it's too large, you could waste valuable time and resources. Find the right sample size for your research in minutes and test the possible results before you begin your study, with IBM SPSS SamplePower.

Strike the right balance among confidence level, statistical power, effect size, and sample size using IBM SPSS SamplePower. Compare the effects of different study parameters with its flexible analytical tools. And with an interactive guide and built-in help features, you won't lose time getting up to speed.

SamplePower is designed to cover:

  • Means and differences in means
  • Proportions and differences in proportions
  • Correlation
  • One-way and factorial Analysis of Variance (ANOVA)
  • Analysis of Covariance (ANCOVA)
  • Regression and logistical regression
  • Survival analysis
  • Equivalence tests

SamplePower was developed by a team of experts that includes Michael Borenstein, Hannah Rothstein, David Schoenfeld, Larry Hedges and Jacob Cohen, author of Statistical Power Analysis for the Behavioral Sciences.



Get Precise Results Faster with Flexible, Efficient Tools

IBM SPSS SamplePower is packed with features designed to make finding accurate sample sizes easy. It has two interfaces – the “classic” interface for those familiar with power analysis and an “easy” interface that walks you through the more common procedures. Either interface explains terms and takes you through the steps necessary to determine an effective sample size – giving you clear, precise answers to move forward with your research.

The 'easy' interface prompts you with a series of simple questions and provides an executive summary of the rationale for the sample size, as well as a detailed report

The “easy” interface prompts you with a series of simple questions and provides an executive summary of the rationale for the sample size, as well as a detailed report.


Make Informed Decisions at Every Step

IBM SPSS SamplePower's interactive summary panel gives you concise summaries of power and precision at any point, so you can see how each decision affects your results.

IBM SPSS SamplePower's interactive guide, which helps you determine an effective sample size step-by-step

IBM SPSS SamplePower's interactive guide, which helps you determine an effective sample size step-by-step.


Compare Results Before You Begin Your Research

The stored scenarios tool gives you optimum control over the flow of your research. You can vary alpha level, power, effect size or sample size in the main screen and store your results as you continue.



See How Your Research Criteria Will Affect Power

Tables and graphs created with IBM SPSS SamplePower enable you to easily assess how different combinations of research parameters (such as proposed sample size, alpha levels and duration) will affect your statistical power.

This illustration shows how the sample size varies as other settings, such as alpha, are changed. Different combinations of research parameters will affect your statistical power

This illustration shows how the sample size varies as other settings, such as alpha, are changed. Different combinations of research parameters will affect your statistical power.


Get Accurate Guidance with Cohen's Effect Sizes

IBM SPSS SamplePower's Tool menu provides Cohen's effect size conventions, which allow you to determine effect sizes for particular tests by simply clicking on an icon. Cohen's effect size provides users with a "rule-of-thumb" for determining otherwise ambiguous "small," "medium" and "large" effect sizes. Plug these effect sizes into the main screen to see how varying the effect size affects power or precision.

IBM SPSS SamplePower guides you through Cohen's effect sizes

IBM SPSS SamplePower guides you through Cohen's effect sizes.


Find Sample Sizes in One Mouseclick

IBM SPSS SamplePower's Find N tool finds the sample size for the default power setting in one click. You also have the flexibility to choose different power size settings to compare results.

IBM SPSS SamplePower is the front end of a complete line of research and analysis software from SPSS, an IBM Company. Whether you’re an advanced or beginning statistician or researcher, you can easily identify the appropriate sample size – every time – with IBM SPSS SamplePower.

IBM SPSS SamplePower finds the sample size for the default power setting quickly and easily.

IBM SPSS SamplePower finds the sample size for the default power setting quickly and easily.



  • Operating system: Microsoft® Windows® 7, Windows® Vista®, Windows XP or Windows 2000
  • Pentium-class processor
  • 16 MB RAM
  • 30 MB drive space
  • SVGA monitor