Calculating your own odds

[trevo]

Not sure where to post this but this seems to be applicable. New to all this so bear with me :D How do you guys go about calculating your own odds for a particular event? For example, there's a match and the over/under 2.5 market is 1.87/2.12. Now, I don't have any ratings or anything like that, I just simply look at the games played previously, look at the lineups, who's injured, the importance of the game and all that. How do I go about giving all that a percentage? In my head I'm saying there's a 60% chance of the game having over 2.5 goals but that's just a really rough (and silly) way of expressing my feeling on the numerous factors involved. And hi all :)

[trevo]

Re: Calculating your own odds Sorry to bump this but I have another question which might be a bit easier to answer. I've done a rough calculation for a football match (home-draw-away) based on recent form only, just to give myself some sort of base to work off. Now, there's a number of factors that I haven't accounted for but would like to, e.g. team lineups, injuries, etc. How do I factor these in to my calculations? Let's say there my workings are looking like this at the moment: Home 1.59 / Draw 5.26 / Away 5.55 But I want to adjust for some of the factors mentioned above. Let's say that the home team has 1 key player missing through injury (and I feel that this should reduce the home teams chances of winning by 5%), do I adjust all three (i.e. Home, Draw and Away) by going Home odds +5%, Draw odds -2.5% and Away odds -2.5%? I know this is extremely rough and basic but I'd like to know if I'm going in the 'right' direction. Home 1.67 / Draw / 5.13 / Away 5.41