Along with gender and race, I am using summated scores from the Climate Change Anxiety Scale and the ASES (academic self-efficacy inventory) all as predictor variables. My dependent variable is YES/NO to choosing a Natural Science major.
Yes, it is acceptable to use summated Likert scaling scores as continuous data in a logistic regression. However, it is important to keep in mind that when using Likert scales, the numeric values assigned to the response categories are arbitrary and do not necessarily represent a linear increase in the underlying construct. Therefore, it would be important to analyze the data carefully to ensure that the results are valid and meaningful.
As Peter Donkor opined, output scores from Likert scale can be used as continuous data . Transformation of
a data set to scores gives it random characteristics. That is why data scores from PCA can be used to create new variables which are independent of each other.
I expect to run the logistic regression in SPSS. So I assume that I can still treat the summated scores as an ordinal measure. Is Peter suggesting that I examine the distribution of summated scores for some measure of normality? I don't understand what Peter means by a linear increase. Of course, the distribution of summated scores may be non-normal, depending on the responses to anxiety levels from the Climate Change Anxiety Scaling and the scaling from the self-efficacy inventory.
@Hamilton, PCA is the abbreviation for an analysis called principal component analysis in statistical analyses. Do not worry about if you don't yet know about it.
Your used summated scores as input data in your analysis. This not the same as the output scores after your analysis.
In effect, @Hamilton, your raw summated scores should not be used as they are in nominal data form for regression analysis. They need to be transformed to interval data.
How do I transform raw summated scores into interval data?
With that said, Tabachnick & Fidell (Using multivariate statistics, 4th ed.) state that predictor variables can be continuous, discrete, dichotomous or mixed...and that the predictors do not have to be normally distributed, linearly related, or of equal variance. I would think that summated scores from Likert scaling responses would be deemed viable under these conditions. Ordinal data are discrete data...and almost all studies that I have read accept summated scores as much more valid and reliable than a single score from one item. When we summate Likert scaling scores, we are already treating the data as interval.
Any answer for the first question and any clarifications would be appreciated.