I completed a tasseled cap analysis and have 49 pixel values for greenness for a particular location. I have also determined the percentage impervious cover for the same area using high resolution images from which the impervious surfaces where manually digitized and their total area calculated as a percentage of the total area. How do i run a regression between these two variables since one is pixel values (with both positive and negative fractions) and the other is a single value ( %). I am running the regression to establish the relationship between tasseled cap greenness and percentage imperviousness.