GraphPad Prism

Overview GraphPad Prism, available for both Windows and Mac computers,  combines scientific graphing, comprehensive curve fitting (nonlinear regression), understandable statistics, and data organization. GraphPad Prism was originally designed for experimental biologists in medical schools and drug companies, especially those in pharmacology and physiology. Prism is now used much more broadly by all kinds of biologists, as well as social and physical scientists.  More than 200,000 scientists in over 110 countries rely on Prism to analyze, graph and present their scientific data. It is also widely used by undergraduate and graduate students. Nonlinear regression Nonlinear regression is an important tool in analyzing data, but is often more difficult than it needs to be. No other program simplifies curve fitting like Prism. In fact, you can usually fit curves in a single step. Just select an equation from the extensive list of commonly used equations (or enter your own equation) and Prism does the rest automatically — fits the curve, displays the results as a table, draws the curve on the graph, and interpolates unknown values. Place data for multiple data sets side-by-side on an organized data table, and Prism can fit them all the data sets at once. You can fit the same model separately to each data set, use global nonlinear regression to share parameter values among data sets, or fit different models to different data sets. Don’t be fooled by the simplicity. Prism also gives you many advanced fitting options. It can automatically interpolate unknown values from a standard curve (i.e., to analyze RIA data), compare the fits of two equations using an F test or Akaike’s Information Criterion (AIC), plot residuals, identify outliers, differentially weight data points, test residuals for normality, and much more.

Understandable statistics While it won’t replace a heavy-duty statistics program, Prism lets you easily perform basic statistical tests commonly used by laboratory and clinical researchers. Prism offers t tests, nonparametric comparisons, one- and two-way ANOVA, analysis of contingency tables, and survival analysis. Analysis choices are presented in clear language that avoids unnecessary statistical jargon.

Unlike other programs, Prism provides understandable statistical help when you need it. Press “Learn” from any data analysis dialog and Prism’s online documentation will explain the principles of the analysis to help you make appropriate choices. Once you’ve made your choices, Prism presents the results on organized, easy-to-follow tables. The Prism documentation goes beyond anything you would expect. More than half of it is devoted to thorough explanations of basic statistics and nonlinear curve fitting, to teach you what you need to know to appropriately analyze your data.

Analysis checklists Once you’ve completed the analysis, Prism’s unique analysis checklists help you make sure you chose an analysis appropriate for your experimental design, and that you understand the assumptions behind the analysis.

Retrace every analysis It isn’t really science unless you can document exactly how your data were analyzed. WIth Prism this isn’t a problem. You’ll never wonder how the results got there. Even if the work was done by someone else, you can review (and change) all analysis choices, and see the sequence of analyses (i.e. that the X values were transformed to logarithms before the curve was fit). Similarly, you can easily check if error bars represent the SD or SEM (or something else).

Automation without programming All parts of your Prism project are linked. This means that when you fix a data entry error, Prism automatically updates all results, graphs, and layouts. Another advantage is that you can instantly analyze a repeat experiment. After you’ve polished the analysis and graphing steps with data from one experiment, you don’t have to repeat all those steps. Prism provides several ways to recycle your work — to instantly analyze and graph a repeat experiment, without repeating any tedious steps and without requiring any scripting or programming. Prism comes with three on-line guides (help). You are now viewing the Statistics Guide. • Switch to the Prism User Guide • Switch to the Curve Fitting (Regression) Guide Prism comes with three on-line guides (help). You are now viewing the Curve Fitting (Regression) Guide. • Switch to the Prism User Guide • Switch to the Statistics Guide. RECOMMENDED BOOKS THREE GREAT BOOKS OF STATISTICAL ADVICE After taking courses in statistics, and reading textbooks of statistics, you may still find statistics confusing. What you need is not more information, but rather advice, perspective, and a guide to steer you away from data analysis traps. These three books provide what you need. All three are written for people who already have learned the basics of statistics, but are still struggling with practical issues of data analysis. All three are extremely well written in plain English (without much math), and are quite accessible to scientists. I strongly recommend all three books. Choosing between them is hard, as all three are great. The best way to choose is to read excerpts online.Read More > Making sense of ANOVA Analysis of Variance (ANOVA) is a powerful technique in statistics, but one that can be quite confusing and is often abused. If you want to really understand ANOVA, this clearly written book will help. It explains ANOVA from the perspective of comparing the fit of alternative models, rather than the more conventional approach of dividing variation into its components. It has plenty of math, but explains all concepts in plain English.Read More > An in-depth guide to dose response curves While overkill for most pharmacologists, this is a unique resource for people who need to deal with complex dose-response relationships, including allosteric interactions, synergy, multi-step binding, cubic binding models and much more. It deals only with systems at equilibrium, so does not cover kinetics. If you are curious, start with this chapter, which explains many variations on the Hill equation, and the many uses of the term “logistic”. If you haven’t heard of the Hill equation, this book is not for you!Read More > Try  software free for 30 days