After that, the analysis part is to obtain a simple relation between solar radiation ( and air
temperature As a first step in assessing whether or not there appears to be a strong relationship
between these two variables, we make a scatter plot as shown in Fig. 5. The scatter plot consists of the
data points, where there is a positive and roughly linear relationship between solar radiation and the
increase in air temperature. The three exceptional data points (observations no. 1, 22 and 198) are well
detached from the remainder of the data. These data points are called outliers.