The Power Advantage of Within-Subjects Designs

How to Select the Appropriate Statistical Analysis

How do doctoral students select the appropriate statistical analysis and power analysis for their methodology selection? Selecting the appropriate statistical analysis and sample size is a very common problem for graduate students.  Here is the strategy we use at Statistics Solutions: select the correct test, and then select the correct sample size for that test.

The Power of Power Analysis

How can power analysis help us in designing our method?  Isn’t significance enough?  Not really.  Significance only tells us how unlikely a Type II error would be, given our method—we may still have a potential Type I error.  As well, something can be significant, and not be important.  Cohen (1992) has long argued that significance

Effect Size for Power Analysis

When conducting a power analysis a priori, there are typically three parameters a researcher will need to know to calculate an appropriate sample size to achieve empirical validity.  Those parameters are the alpha value, the power, and the effect size.  The alpha value is the level at which you determine to reject the null hypothesis. 

Determining Sample Size

Getting the most out of surveys requires a few prerequisites. One prerequisite is understanding and determining sample size. It’s funny, our clients typically think they either have too many participants or too few participants, but rarely ask how one calculates the appropriate sample size. The sample size requirement for surveys is important issue in at

Intellectus Statistics: Available Analyses

The current analyses available in Intellectus Statistics are: Descriptive Statistics-Calculates frequencies and percentages for selected nominal and ordinal variables. Calculates means and standard deviations fro selected scale variables. Cronbach’s Alpha-Examines the extent to which a set of scale level variables are consistently scored. Chi-Square Test of Independence-Compares the observed frequencies to expected frequencies of two nominal

Sugar Plums and Sample Size Blues

Its Christmas time again, and a good time to plan getting your dissertation completed, and that pesky scientific merit review, IRB application, concept paper, and dissertation proposal meeting. In the spirit of completing these tasks, there is a consistent problem that I find: graduate students struggle with the sample size determination. [Read More]

Principles, Values, Context and the Dissertation Process

To get what you want out of life, you have to align your values with the principles of the world. Values are what you consider important, and they may or may not be unique to you. You may believe that pain is bad and to be avoided at all costs, while others may believe that pain is an opportunity for a lesson and that it allows you to become stronger. Principles are fundamental truths about the world…[Read More]

Sample Size in Plain English

As a dissertation consultant for over 20 years, I consistently see confusion when it comes to answering a simple question—how many participants do in need? The confusion is reasonable because most programs do not even offer a class in sample size and leave it to the graduate student to figure it out on their own.

Sample Size Calculation

Sample size calculation is very important in statistical inference and findings.  A sample is a subset of the population.  It is through samples that researchers are able to draw specific conclusions regarding the population. Sample size is the size of that sample. Sample size is very important in statistics. Statistics Solutions can assist in choosing