If a team scored the first goal in the first half and hold it until the end of first half, what does that mean? How big is the chance to win that game? Or is there any chance for the opposition team to win it back? How big is that chance? What are the differences in holding 1 goal and 2 goal differences in terms of the percentage of chance to win the game finally? Are 2 goal differences safe enough to win a game? The follow analysis will answer all the questions above by analysing the league 2 result this season (updated to 20/12/2012).
I have compared the half time results with full time results and built a connection between half time leads and full time results by using the goal difference.
When the game was tied at half, there was a 42% chance to have a draw at the end of the game. In other words, there was a 29% chance that one of the two teams won the game finally.
However, if a team is leading by 1 goal at half time, the chance of winning the game increased significantly from 29% to 68% which is a pretty high chance. It is worthy to note that it still had a 8% chance to lose the game even the team had a 1-goal lead at half time. That’s why so many people claimed that the team need a “two-goal cushion” to get the three points. Is “two-goal cushion” a three-point guarantee in league 2? We are going to find out.
When a team was leading by 2 goals at half time, the chance of winning the game increased from 68% to 91%. In other words, it was not a 100% guarantee yet because 6% of teams managed to get a draw finally. Surprisingly, there was still a 3% chance that the leading team eventually lost the game. In short, there was 1 out of 10 chances that the leading team can’t get the three points at the end of the game. The “two-goal cushion” may not be as safe as people thought in League 2.
However, once a team was leading 3 goals at half time, the match is over. No team could manage to get a draw or win it back if they are losing at a 3-goal margin at half time.
Similarly, there were two occasions that a team was leading 4 goals at half time and they all won it eventually.
To summarise, going from a tie to a lead by 1 goal, 2 goals and then 3 goals or more, the chance of winning the game increased from 29% to 68% to 91% and then to 100% eventually. “Three-goal cushion” was a guarantee of the three points instead of two-goal.
In terms of analysis, this analysis could go further in depth by separating the home and away game results to see whether it is easier to hold the lead in home.