Forming Tissue Odds

I will now attempt to explain the basics of forming your own odds. I will use the 4.40 at Limerick on Sunday the 31st March 2019 as the example. This is a handicap chase with 13 runners declared and the idea would be to show you how to very basically form your own the odds for that, race. Now at present this race has no weights declared, no form guides, write ups or little else, so you have to work with what you have.
All we have are the runners names, the trainers details and their official ratings. The runners are at present listed alphabetically, but we form our first market by listing them by their official ratings and price them up accordingly.
Having then listed them, we now go to the bottom rated horse which is in this case Presenting Mahler and alter that runners official rating from 109 to (2), this has meant reducing it by 107. You must now reduce all the other ratings by 107 to obtain a new rating for the rest of the field ,which will give us a workable figure to calculate our first set of odds.

Goulane Chosen1423515.48%11-2
Tycoon Prince1373013.27%13-2
Lucky Pat1362912.83%7-1
Impact Factor1342711.94%15-2
Nearly Nama'd128219.29%10-1
Dakota Moirette127208.84%10-1
Reach Up121146.19%16-1
Call A Cab120135.75%16-1
Carrig Cathal120135.75%16-1
All The Chimneys11252.21%40-1
Alto Esqua11141.77%50-1
Presenting Mahler10920.88%100-1

To obtain our first set of odds ,we now have to convert our new ratings into a % ,so by totalling all of our new ratings for the thirteen runners we get a total sum of 226. So, by dividing each new rating by 2.26 we will achieve a % rating for each runner. This will form a book (set of odds) to 100% .Unfortunately ,although this would be fair, the bookmakers have to build in a profit margin of usually about 10% ,but we will cover that in part two.
Finally ,we compare the % rating to this chart Odds to Percentages (listed in the Reference and Help section) to obtain the odds for each runner. This is only part one of this thread , I will now wait for the handicapper to allot the weights for the race and that is hopefully where it all changes. You can usually work out what the weights would be from the official ratings but lets take it a step at a time.