PJC_83

Usually 1.05 - 1.14 for Over 7.5, although that fluctuates wildly point by point.

I've always been a football man, but I find my judgment clouded at times by gut instinct, rather than what the stats say (I know stats aren't everything).
I'm a big fan of data analysis, and the patterns that they show, so I decided to apply them to a game I'm less up-to-date with, and that's Tennis.
I know the rules of tennis, the patterns of play, the fundamentals, but my knowledge of the actual players isn't great. I could probably name 50 of both genders combined, maximum.
Another thing that interests me about tennis betting is that there has to be a result. An underdog cannot play for a draw in tennis like they can in football. Football can have overwhelming domination by a favourite, yet finish 0-0. In Tennis, there has to be a result, therefore each set someone will reach at least 6 games (barring retirement).
I analysed all the match data from 2019, looking only at matches that completed.
1117 Men's matches, and 1016 Women's.
I'm an over/unders man, and a short odds gambler, so I am specifically looking at the number of games in the 2nd set. Looking at the 2nd set I find more consistent, because you can analyse the 1st set performance and take that into account. If someone was smashed 6-0 in the 1st set, then the likelihood of a 2nd set finishing 7-6 is a lot less than had the 1st set been much closer.
The specific market I'm looking at is Over 7.5 games in the 2nd set, so essentially the set finishing any score other than 6-0 or 6-1.
The data made quite interesting reading:
The total number of games having Over 7.5 in the 2nd Set:
Men's: 993/1117 - 88.9%
Women's: 829/1016 - 81.59%
Men's data breaks down further as follows:
Over 7.5, 2nd set, clay courts: 395/451 - 87.58%
Over 7.5, 2nd set, hard courts: 598/666 - 89.79%
and Women's:
Clay: 308/365 - 84.38%
Hard: 521/651 - 80.03%
So, on the face of this, it indicates that men's games on hard courts tend to be a lot closer than any other match type.
I then looked at taking the pre-match odds into consideration. I looked at matches where the favourite was priced 1.5 or shorter, and also looked at games where both players were priced between 1.50 - 2.50 (therefore, you'd imagine, closer matches).
Men's:
Under 1.5 Favourite, All Games: 512/586 Over 7.5 2nd set - 87.37%
Under 1.5 Favourite, Clay: 184/216 Over 7.5 2nd set - 85.19%
Under 1.5 Favourite, Hard: 328/370 Over 7.5 2nd set - 88.65%
1.5 - 2.5 Odds, All Games: 426/469 - 90.83% 
1.5 - 2.5 Odds, Clay: 187/208 - 89.90%
1.5 - 2.5 Odds, Hard: 239/261 - 91.57%
Women's:
Under 1.5 Favourite, All Games: 431/536 Over 7.5 2nd set - 80.41%
Under 1.5 Favourite, Clay: 146/179 Over 7.5 2nd set - 81.56%
Under 1.5 Favourite, Hard: 285/357 Over 7.5 2nd set - 79.83%
1.5 - 2.5 Odds, All Games: 354/429 - 82.52% 
1.5 - 2.5 Odds, Clay: 148/170 - 87.06%
1.5 - 2.5 Odds, Hard: 206/259 - 79.54%
Conclusions at this stage: Men's hard court matches with more even odds have a higher chance of going over 7.5 games in the 2nd set than any other conditions.
I then drilled down even further, to look at the chances of over 7.5 games in the 2nd set, depending on the number of games in the 1st set.
These are the highlights of the findings:
In men's matches, with odds 1.5-2.5, on Hard courts, and where the 1st set finished 7-6, there is a 93.75% chance of the next set having over 7.5 games. However, this is a fairly small field..
In men's matches, 1.5 - 2.5 odds, Hard courts, 1st set had 9+ games. 2nd set chance of over 7.5 is 91.41%. Although this is a decrease from the line above, it does have a larger field (it has occurred 199 times this year from a sample of 217 games).
Taking implied odds into account, 1.09 has implied probability of 91.74%, and 1.1 has implied odds of 90.91%, so any odds 1.1 or longer for over 7.5 2nd set games is value.
 
 
Hope this makes sense, I'll add more as I go.