Scatter plot diagram
- 2. Scatter plot diagram • A scatter plot is a mathematical diagram using Cartesian coordinates to display values for typically two variables for a set of data.
- 3. When to use Scatter diagram • Paired numerical data • To determine whether the two variable are related • To identify potential root-cause of problems (whether cause and effect are related) • In regression model building, to decide whether to consider variables for regression
- 5. Positive correlation Correlation describes the type of relationship between two data sets. Positive correlation is a relationship between two variables in which both variables move in the same direction
- 6. Age of car (years) Valueofcar(₹) Negative correlation is a relationship between two variables in which one variable increases as the other decreases, and vice versa. Example: 1. As a car gets older it is worth less 2. The weight of a truck (T) and mileage (kmpl) Negative correlation
- 7. No correlation no relationship, connection between the two variables Correlation = 0
- 8. Why to use Scatter diagram • Plotting a scatter diagram is first step in looking for relationship between two variables • Assessing strength of relationship (strong, neutral, weak) • Exploring trend and making prediction • To find out any outliers
- 9. Trend • The line of best fit is the line that comes closest to all the points on a scatter plot. • Lines of best fit can be used to make predictions • How much money we can predict to collect if 60 visitors attended? No correlation
- 10. Finding outliers Outliers are observations which are far enough away from the mean that they are noticeably different. Away from the cluster Application: • Might be errors in data entry • They indicators that something is wrong with our model. • To detect fraudlet We can discard them without harm to study With outlier: average = 2.8 Without outlier: average = 2.1
- 11. Positive correlation Negative correlation as one data set increase decreases. No correlation • If variables are correlated, points fall in a line or curve • Better the correlation, tighter the points will hug the line Reading a Scatter diagram