Businesses nowadays tend to ask their customers to grade a product or a service they have experienced, usually that grading is a number of stars on a scale of 5. When an individual grades a product, that grade goes into a system that calculates the average of all given grades and expose it to the next individual, and so on. Through primary data we estimated what could be a realistic distribution of uninfluenced grades as well as a realistic degree of social influence. This thesis aims to understand the social influence on individual grades and to what extent the order in which graders come may bias the aggregate grade. In addition, we aim to apply mathematical analysis and simulations to examine the social influence of a planted grade on aggregate grade, depending on the strength of social influence and the total number of graders. It was concluded that ordering the same set of individuals in different ways will give different aggregate grades, mostly biased when ordering from largest to smallest and the other way around. In addition, we presented a perception on how large a planted grade can affect the aggregate grade, studying different main factors such as the degree of social influence and total number of graders.