# Correlating time of possession with scoring in rugby

I am exploring the relationship between time of possession and scoring in rugby. Each match has two teams that appear on subsequent rows in the data set:

       Match Event  Team             Points Possession
0      1     Dubai  SOUTH AFRICA      36    209
1      1     Dubai      PORTUGAL       0    113
2      2     Dubai         WALES      14    231
3      2     Dubai        CANADA      19    197
4      3     Dubai          FIJI      54    218
5      3     Dubai        FRANCE       7    141
6      4     Dubai     ARGENTINA      17    238
7      4     Dubai        BRAZIL       5    146


I subtract the second team's points and possession from the first team's to find the point and possession differential for each match:

Match,Points,Time
0,36,96
1,-5,34
2,47,77
3,12,92
4,-7,-11


I plot the possession differential against the point differential in a scatterplot to visualize the relationship, add a best fit line, then use pearsonc to characterize the relationship with a single number.

What are the drawbacks of this approach?

Is there a better way to characterize the relationship?

Would it be better to normalize the data to the match winners so that all point values are positive?