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.
When you walk on it, it will release and although you make a perfect grout phase, the grout line will crack in two days because the tile is loose. You will need to take up the bad tile, grind out the old thinset and do it right. Short time tile jobs are done with a product named SPEEDSET.