In SPSS, we sometimes encounter variables that are negatively coded: lower values indicate higher agreement or more positive sentiments. Although this is not really “wrong” in any way, positive coding is more intuitive. Especially when reporting means over variables, most readers naturally expect higher means to indicate something better, not worse. So what’s the best way to reverse code variables? […]
The assumption of equal intervals says that all distances between adjacent answer categories are equal in the repondents’ perception. This assumption is an attempt to justify treating ordinal variables as if they were metric variables. Doing so enables one to compute means, standard deviations and Pearson correlations on ordinal variables. This is simpler than using more appropriate techniques. Assumption of Equal […]
A course was evaluated by 183 students. The data are in course_evaluation.sav, part of which is shown below. The teacher wants to know the average age of his students but we only have their date of birth. 1. Ensure Date of Birth is a Date Variable The first thing we’ll do is check if date of […]
Measurement levels refer to different types of variables that imply how to analyze them. Standard textbooks distinguish 4 such measurement levels or variable types. From low to high, these are nominal variables; ordinal variables; interval variables; ratio variables. The “higher” the measurement level, the more information a variable holds. The simple flowchart below shows how […]
