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Checking the Additional Assumptions of a MANOVA

So a MANOVA is typically seen as an extension of an ANOVA that has more than one continuous variable. The typical assumptions of an ANOVA should be checked, such as normality, equality of variance, and univariate outliers. However, there are additional assumptions that should be checked when conducting a MANOVA.

The additional assumptions of the MANOVA include:

• Absence of multivariate outliers
• Linearity
• Absence of multicollinearity
• Equality of covariance matrices

Absence of multivariate outliers is checked by assessing Mahalanobis Distances among the participants. To do this in SPSS, run a multiple linear regression with all of the dependent variables of the MANOVA as the independent variables of the multiple linear regression. The dependent variable would be simply an ID variable. There is an option in SPSS to save the Mahalanobis Distances when running the regression. Once this is done, sort the Mahalanobis Distances from greatest to least. To identify an outlier, the critical chi square value must be known. This is derived from the critical chi square value at p = .001 with the degrees of freedom being the number of dependent variables. With 3 variables, the critical value is 16.27, so any participants with a Mahalanobis Distance value greater than 16.27 should be removed.

Linearity assumes that all of the dependent variables are linearly related to each other. This can be checked by conducting a scatterplot matrix between the dependent variables. Linearity should be met for each group of the MANOVA separately.

Absence of multicollinearity is checked by conducting correlations among the dependent variables. The dependent variables should all be moderately related, but any correlation over .80 presents a concern for multicollinearity.

Equality of covariance matrices is an assumption checked by running a Box’s M test. Unlike most tests, the Box’s M test tends to be very strict, and thus the level of significance is typically .001. So as long as the p value for the test is above .001, the assumption is met.

Dissertation Statistics

Dissertation statistics are the statistics that are necessary to prove your thesis, and dissertation statistics are the most crucial part of your dissertation. And though dissertation statistics are the most critical part of any dissertation, many doctoral students neither have the training nor the experience with statistics to perform the dissertation statistics correctly.

Statistics Solutions is the country's leader in dissertation statistics consulting. Contact Statistics Solutions today for a free 30-minute consultation.

Dissertation statistics are difficult and challenging for doctoral students because for many doctoral students, dissertation statistics are the first time that the student encounters so much data and so much information that needs to be processed, analyzed and collated. And because many doctoral students do not have the experience necessary to perform the dissertation statistics, oftentimes doctoral students make mistakes and these mistakes on the dissertation statistics cause the doctoral student to delay the completion of the doctoral dissertation.

The best way to ensure that the dissertation statistics are done correctly and the best way to ensure that the doctoral student finishes the dissertation on-time and with success is to get help on the dissertation statistics. Help on the dissertation statistics usually comes in the form of a dissertation consultant and a dissertation consultant can be the difference between a student finishing in a timely manner and with success, and a student struggling indefinitely through every single aspect of the dissertation and through every single aspect of the dissertation statistics.

A dissertation consultant will guide a student through every part of the dissertation writing process, including offering invaluable help to every doctoral student through the statistical processes that are necessary for all dissertations. With the help of a dissertation consultant, the student will be able to perform the complicated statistical procedures and dissertation statistics that accompany all dissertations. This individual help includes help on the choosing of the topic, on the research that is necessary before any student begins the dissertation, on the putting together of the proposal for the dissertation, on the dissertation methodology section, on the sample size justification, on the gathering of the data, on the analyzing of that data, on the application of the data to the dissertation, and on the proofreading of the entire doctoral dissertation.

Clearly, then, a dissertation consultant can take a doctoral degree seeking student through every single step of the dissertation and a dissertation consultant can ensure and guarantee that a doctoral degree seeking student finishes the dissertation with success.

Because it is so easy to get help on the dissertation statistics, there is no reason not to seek help from a dissertation consultant. Not only will a dissertation consultant help a student through the lengthy and difficult dissertation statistics, however, a dissertation consultant will also instruct the student as he or she is working on the dissertation statistics. Because a student must be prepared to orally defend his or her dissertation and his or her dissertation statistics, this instruction on the dissertation statistics is often the most important aspect of getting a dissertation consultant to help you with your dissertation. All students must pass the oral defense of the dissertation and all students must be prepared to explain every single statistical procedure that occurs in the dissertation. The dissertation consultant will make sure that each and every student who seeks their help will be prepared for this oral defense of the dissertation.