If Q is less than the limit, the two variables are related.Look up the limit for N on the trend test table.Find the smaller sum and the total of points in all quadrants.Ī = points in upper left + points in lower rightī = points in upper right + points in lower left Add the diagonally opposite quadrants.If number of points is odd, draw the line through the middle point.Count X/2 points from left to right and draw a vertical line.Count X/2 points from top to bottom and draw a horizontal line.Divide points on the graph into four quadrants.You may wish to use regression or correlation analysis now. If the data clearly form a line or a curve, you may stop because variables are correlated. Look at the pattern of points to see if a relationship is obvious.(If two dots fall together, put them side by side, touching, so that you can see both.) For each pair of data, put a dot or a symbol where the x-axis value intersects the y-axis value. Draw a graph with the independent variable on the horizontal axis and the dependent variable on the vertical axis.Collect pairs of data where a relationship is suspected.When testing for autocorrelation before constructing a control chart.When determining whether two effects that appear to be related both occur with the same cause.After brainstorming causes and effects using a fishbone diagram to determine objectively whether a particular cause and effect are related.When trying to identify potential root causes of problems.When trying to determine whether the two variables are related, such as:.When your dependent variable may have multiple values for each value of your independent variable.This cause analysis tool is considered one of the seven basic quality tools. The better the correlation, the tighter the points will hug the line. If the variables are correlated, the points will fall along a line or curve. The scatter diagram graphs pairs of numerical data, with one variable on each axis, to look for a relationship between them. Quality Glossary Definition: Scatter diagram

Plot two scatter plots same graph r