Autonomous investment is indicated by the intercept. 1  An Induced Slope: The slope of the investment equation (f) measures the change in investment resulting from a change in income. If income changes by $1, then investment changes by $f.
24 to 48 Hours. You should wait at least 24 hours before grouting the tiles. You may notice that the edges of the thinset or the thinset showing through the grout lines looks dry. Don't be fooled by this. The thinset under the tiles isn't receiving as much air as the edges and is therefor not fully cured.
I've done a lot of tiling over the years. The first thing you need to know is that the guy at Home Depot has probably never done one single bit of tile work. That said, if you want to do it right, don't walk on the floor for 12 hours. Wait for another 24-48 hours before you seal the grout.