A Variable That Inadvertently Causes an Experimental Result Is
If the elasticity of demand curve for buckwheat is -1.25 at all prices higher than the current price, we would expect that when bad weather reduces the size of the buckwheat crop, total revenue of buckwheat producers will fall.
If the equation for the demand curve is q = 20 - 2p, then the ratio of marginal revenue to price is constant as price changes.
If the equation for the demand curve is q = 50 - 4p, then the ratio of marginal revenue to price is constant as price changes.
If a rational consumer must consume either zero or one unit of a good, then an increase in the price of that good with no change in income or in other prices can never lead to an increase in the consumer's demand for it.