The answer is, "Just noticeable differences."
Weber's law was named after Ernst Weber, a German psychologist. The law postulates that the strength and intensity needed to identify changes in a stimulant correlates to the magnitude of the stimulant. In other words, the more severe a stimulus is, a greater change needs to be made for it to be noticed.
Dhiki - used to grind rice, grains etc
jato - also used for grinding purposes
A demand schedule generally focuses on overall demand of a product or service. That is, in units or monetary value. This could be over time, yearly, quarterly, or semianually.