A scatter diagram is used for trend analysis. this diagram plots data on an x/y axis to identify the correlation between the parameters plotted on these axes. It helps in forecasting future trends. Acontrol chart is a graphic display of process results shown over a period of time, which helps determine if the process is in control. It shows if differences in results are due to random causes or unusual events that need to be identified and rectified. Pareto diagrams are bar charts based on the pareto 80/20 law, according to which 80 percent of problems stem from 20 percent of the causes. It shows problems ranked in descending order of significance and identifies the most significant cause that must be rectified first. Afishbone diagram is a cause-and-effect diagram used to identify the root causes of a quality problem. this diagram, also known as an ishikawa diagram, shows how various factors are linked to potential problems.