verifying slope data with contours?

Discussion created by agray7501 on May 27, 2010
I have created slope data 10x10 grid with spatial analyst and want to verify that against the slope of the contours.

The grid was originally from a USGS DEM 10meter. Then it was re-projected and the slope calculations were done on the reprojected grid. Used 3.280 to convert from meters to feet.

The cells within the area that I am looking are showing percentage of slope at about 11-12% but when I calculate the slope using our 5ft contours in the same area, I am getting about 23% slope..

Which one is correct?