my scatterplot that shows the relationship between my principal component and one of my questionnaire items looks strange. The scatterplot between two of my principal components looks great (see second image).

The item is measured on a Likert scale from 1 to 5 (1 = strongly disagree, 5 = strongly agree). The histogram of this item also has many gaps between the bars, which is strange to me too.

Please let me know which specific output you still need to figure this out.

Thanks

CodePudding user response：

For reproducibility, it is best if you provide a piece of the database you are using to make these scatterplots. It would also be great if you include the axes titles inside the graph.

To be honest, I dont see anything wrong with the first figure. Variable y (the questionare item) is a discrete variable between 1 and 5. It make sense that one result from the PC1 is match with more than one of the values of the item questionare.

CodePudding user response：

That is because the principal components are both metric and the Likert scale is ordinal, so the values can only be integers from 1-5. In this regard the Scatterplot does not look strange but it might be the wrong type of plot. If you anyway want to use a scatterplot you can use jitter(var, 0.3) on the ordinal variable when creating the plot. 0.3 is just a suggestion, it's best if you just try what works. As you didn't provide a reproducible example I wasn't able to try it out.