linewidths which is used to indicate the line width of the marker edges edgecolors indicates the color to use for the marker edges if different from the fill colour used for the marker (indicates by the parameter ' 'when to use scatter graphs useful question to consider is when should scatter plot be usedin general scatter plats are used when it is necessary to show the relationship between two variables scatter plots are sometimes called correlation plots because they show how two variables are correlated in many cases trend can be discerned between the points plotted on scatter chart (although there may be outlying valuesto help visualise the trend it can be useful to draw trend line along with the scatter graph the trend line helps to make the relationship of the scatter plots to the general trend clearer the following chart represents set of values as scatter graph and draws the trend line of this scatter graph as can be seen some values are closer to the trendline than others the trend line has been created in this case using the numpy function polyfit(