How do I select a statistical consultant?

It only makes sense to hire a company where the consultant has dealt with dissertation committees (i.e., the consulting company have employees who have a doctorate degree) and has expertise in statistics (Ph.D. is preferred). Confirm their credentials—if they say they have a degree from Harvard Department of Statistics—call Harvard’s statistics department top confirm (I have a Ph.D. in Clinical Psychology from an APA-accredited program at Miami University in Oxford, Ohio).

Make sure the company is responsive, patient with answering your questions, and trust your experience with the potential company. Remember, you are the customer!

If you have questions, please feel free to call us at 877.437.8622 or visit our website at http://www.statisticssolutions.com/

How do I assess the assumptions of an independent sample t-test or ANOVA?

There are three main assumptions in these statistical techniques. The first, and most important, is independent of observations. That is, one participant does not influence the score of another participant. The second assumption is homogeneity of variance. ANOVA assumption can be tested by checking the SPSS box for “homogeneity tests.” For t-test, SPSS provides the Levene test as a default. The third assumption is normality assumption. This can be tested with a one-sample KS test. For more information you can email us at www.StatisticsSolutions.com or call 877-437-8622.

How do I calculate the sample size for my research?

Sample size is an elusive topic. While completing my master’s and doctorate degrees, the issue never arose! First, the sample size is determined in coordination with a preselected power (typically .80), alpha (typically .05), and an effect size (typically .50). Secondly, the sample size is different for different analyses (e.g., for multiple regression, t-tests, etc.) At www.StatisticsSolutions.com we use Cohen’s articles on statistical power and G-power (online) to calculate the required N. For more information you can email us at www.StatisticsSolutions.com or call us at 877-437-8622.