# 8-Jul-2008 Choosing the correct statistical test

Many Analyse-it users readily admit their statistics knowledge is a little rusty, usually because it’s 10 years or more since their last statistics course. Should I use the t-test, Mann-Whitney, or Wilcoxon test? The names of the tests aren’t exactly helpful, nor do they give you any clue of the assumptions that must be met to use the test.

That’s why we devised the **Statistical Test Advisor**.

It’s a simple interactive wizard that asks what you want to do, what data you’ve observed, checks which pre-test assumptions can be met, then tells you the best statistical test to use. Using the advisor you can be confident you’re using the correct statistical test -- or even use it to check if your statistics knowledge really is as rusty as you think!

Try it for yourself now:

/support/advisor/test-advisor.aspx

Bear in mind this is only a simple prototype at the moment. Eventually the advisor will integrate into Analyse-it, leading you to help and tutorials showing you how to use the recommended test and interpret the statistics. You’ll also notice the advisor recommends tests that will be new to Analyse-it 3.

So now it’s over to you. What do you think to the test advisor? Will you find this useful? Are the questions logical? Is the terminology clear or do we need to explain the terms used? Finally, have we missed anything you think should be included?

Let us know what you think, good or bad. Post your comments below.

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## Comments

Hopefully the Statistical test advisor covers the who, what, when where and why questions you raise. Knowing when to use a particular statistical test, and especially the assumptions that must be met, is probably the area where most users struggle. As you say, there aren't many books that cover all those points -- David Sheskin's book (we'll post a review shortly) is probably the exception to that rule.

As for interpretation of the results, that's where the advisor will lead to the Analyse-it help. We did try including more help and advice in the advisor itself, but since each page is very much like a PowerPoint slide, space is very limited. Instead we'll us the help to cover concepts such as normality, similar shape distributions, heteroscedascity in more detail, as well as provide guidance on how to interpret each and every statistic Analyse-it shows.

I know in reality, there are too many variabilities in the data itself and what goals researchers are trying to achieve. Thanks for letting a Grad Student who has been wrestling with these things for the past two years vent.

I do think the Statistical Advisor is a good idea in helping researchers, especially those that don't have a strong stats background, organize their thoughts about statistical procedure.

Thanks for your patience (for the rant) and for a good product!.

Gordon

We are planning to provide links from the advisor to more detailed help, to more fully explain each step/question and clarify the terminology used. Where necessary, we'll also explain how you can use statistical tests to, for example, verify normality, examine the shape of the sample distribution, and verify other pre-test assumptions.

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