Power Analysis
A statistical test's power is the probability that the test procedure will result in statistical significance. Power is related to the sample size, the size of the type I (alpha) error, the actual size of the effect, and the size of experimental error. All of these must be considered in order to calculate statistical power.

As statistical significance is usually the desired outcome, planning and running a study to achieve a high power is of prime importance to the researcher. Because of the complexity of the calculations, the determination of the power is often ignored or only a casual attempt is made at its calculation by adopting some, so-called, "rule-of-thumb."

PASS Beats the Competition!
PASS performs power analysis and calculates sample sizes. Use it before you begin a study to calculate an appropriate sample size (it meets the requirements of government agencies that demand technical justification of the sample size you have used). Use it after a study to determine if your sample size was large enough.

PASS lets you solve for power, sample size, effect size, and alpha level. It  automatically displays charts and graphs along with numeric tables and text summaries in a portable format that is cut and paste compatible with all word processors so you can easily include the results in your proposal.

PASS is a standalone system. Although it is integrated with NCSS, you do not have to own NCSS to run it. You can use it with any statistical software you want. PASS 2008 runs under Windows Vista, XP, 2000, NT, ME, 98, and 95.

PASS is accurate. It has been extensively verified using books and reference articles. Proof of the accuracy of each procedure is included in the extensive documentation.

PASS comes with three manuals that contain tutorials, examples, annotated output, references, formulas, verification, and complete instructions on each procedure. And, if you cannot find an answer in the manual, our free technical support staff (which includes three PhD statisticians) is available.

No other program calculates sample sizes and power for as many different statistical procedures as does PASS. Specifying your input is easy, especially with the online help and manual.

Choose PASS. It's more comprehensive, easier-to-use, accurate, and less expensive than any other sample size program on the market.

Features. PASS is the most comprehensive sample size program available with over 150 statistical procedures. Accuracy of each procedures is well validated. PASS is easy to learn and use. PASS is a standalone software package (no other stat package is required). PASS easily produces sharp, flexible graphics. PASS output is easily transferred to popular word processors and presentation software such as PowerPoint.

Pricing. With electronic documentation, PASS 2008 sells for $749.95 (academic/government) and $999.95 (commercial), a price much lower than the competition's. With printed manuals, PASS 2008 sells for $849.95 (academic/government) and $1,099.95 (commercial). We also offer special pricing for current students. Call for details. Multiple-user discounts are also available. You can order from our secure online order form, by email, by fax, or over the phone.

7-Day Trial. Go ahead, download a 7-day trial version of PASS today. During the trial period, the spreadsheet is limited to 100 rows of data. You can try all of the statistical procedures, import/export your data, and print your reports. This is an excellent way to become acquainted with PASS.

Download a 7-day trial copy of PASS 2008

Place an order using our secure online order form

Procedure Window
Once you select a procedure from the tree or menus, the corresponding Procedure Window appears. This window lets you quickly and easily specify the power analysis or sample size parameters. The immediate help window on the right gives you a brief explanation of each option as the mouse passes over it. You can save the settings in a template file for future use.

Output
All reports are displayed using our built-in Word Processor. You can quickly view, edit, save, and print your output. Reports are stored in the generic RTF (rich text) format that can be read by most word processors, so you can easily save PASS reports for further use in Word or WordPerfect. The output document mixes text and graphs together. The text portions of the reports are formatted using tabs (not spaces), so they are easily reformatted.