●Line chart
A “line chart” typically shows a numerical value along one axis an
elapsed time along the other, with a line connecting points plotted at each
time marker, giving this graph its name. It is used to represent trends over
time, as with changes during the course of a year.
Minimum temperature by region (2009)
℃
25
20
15
Region A
Region B
10
Region C
5
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Reference
●Regression analysis
“Regression analysis” expresses a correlation between two kinds of data
that are plotted on a scatter diagram, using a straight line to show the relationship.
If the two kinds of data are “x” and “y,” then the linear regression can be
expressed as “y=ax+b.” In this case, “a” is the “slope” of the linear regression, and “b” is the “y-intercept.”
For example, in this graph, if the annual average temperatures can be predicted, beverage sales can also be predicted, which would help determine
quantities of products to order.
A linear regression is a straight line with the shortest distance to each
point, which is calculated using the “least-squares method.”
Least-squares method
y
y=ax+b
Cold-beverage sales profit
The “least-squares method” draws a
straight line that has the smallest total
value for the squares of the distances
between plotted points and the regressed line.
Linear regression
x
Temperature
31