Here's how I would go about setting up a Market for Race 5 at Sandown Park today.
Why I chose this particular Race is because I am familiar with many of the dogs running in it.
I feel that I can get a most accurate assessment with dogs that I have heard or seen previously.

I get my information from the Online Database at grv.com.au
They call it eform.
If you wish, you can download a dogs entire Race History.
I download the previous 9 months of Form for each dog.
I then eliminate any more than the most recent 25 runs if there are more than that.
Then I go through the Form of each dog, one at a time.
I try to find a race that is most similar to todays Track and Distance.
I also take much notice of the most recent half a dozen runs.
Current Form is much more important than Old Form.

No 1 DEE PRINCE

Only effort at Sandown was a Last after beginning slowly.
Has had 3 runs since for a win and a second.
So it obviously has some ability and the Sandown run will certainly be improved on.
So the hunt is on to find a more suitable run to guage this dogs ability.
I've gone on its last run at The Meadows over 600 metres where it ran 2nd in a time of 35.02 seconds.
What I do next is look this up on a Chart to see how it compares with the Track and Distance of todays Race.

WHAT CHART?
Make yourself one.
I started with using the Track Records for each of the Distances and Tracks in Australia.
Then with some tinkering, I have what I use now.

It comes up as being equal to a time of 30.4 seconds.
I added a half a length to this time to allow for the different distance and track todays Race.
So I expect This dog to run 30.43 seconds today.

And this is done for every dog in the race.

No 2 SHANLYN COBRA

Ran 2nd here in February in 30.14 seconds out of this Box
Failed twice after that but had outside Boxes.
Then had a few tries over 400 metre races and last start found bother at Traralgon over the 513 and finished 3rd.
I've penalized the dog 3 lengths for the 2 Failures and expect it to run 30.32 seconds today.
Box Draw is a HUGE help.

No 8 OUR IMMY

This bloke failed badly at 2 tries here.One of them was 2 starts ago.
Best Form is over the shorter 400 metres at SALe where it recorded a Hard To Believe 24.80 second win.
I'm going on its last start Meadows run where it ran 4th in 30.62
It was interfered with in the run but I didn't allow for that because it deserves an equal penalty for failing badly at Sandown previously.
I expect a run of 30.42 today.

No 5 BLACK NEWFIRE

Best Time was a 4th here recently in 30.26
Failed twice here since but ran well at The Meadows beating Dee Prince by a length and a half.
I expect 30.33 here today, the same as Dee Prince less the length and a half Margin.
The Box Draw will be a burden.

No 3 REGATTA BALE

30.38 last start here after copping some problems.
I expect similar problems and a similar time.

No 4 GHOST PIRATE

This one is hard to line up.Has no Form at Sandown.
Form is more over the 400 metres but has won at 513 at Traralgon a while back.Failed there twice since.
30.47 is my guesstimate, but am hoping for start problems because it is capable of much better on its 400 metre times.

I don't have time to go further with this now, but I will not listen to the result and will give my summary for the other dogs later today.
These times are used in conjunction with the Greyhounds ability to get out of the Boxes quickly and cleanly.
Could be wrong, but I would guess the Check will come up at about a $3 Chance in my Final Market, so if you Fancy it at all....GET ON!!!

2 to beat 1,3 and 5 seems the good guess.