When good is not enough, Camshaft time again.

My engine dyno has a depac data acquisition. It has three options for correction factor. Std. j607, Sae J1349 and DIN. I haven't ever used DIN. It is metric correcting to 760mm., dry air and 20 degrees Celsius. J607 (The old standard) corrects to 29.92", dry air and 60 degrees. J1349 (new standard) corrects to 29.53", dry air and 77 degrees.
What I use 90% of the time is J1349. J1349 gives lower numbers than J607. It is a newer version of correction that sae came up with that is supposed to be more accurate. I think there are even newer and or different versions than J1349. I did a deep dive on correction factors some years back so my memory may not serve me well.
Why I use J1349 is because when I got my first dyno this was the advice given me by Depac Dave and other dyno operators who helped me get started. And my own research led me the same direction. First let me say that there is nothing wrong with using J607 and in my opinion either factor is better than no correction factor if you want to be able to compare your own data on different days where conditions may be different.
A correction factor is an number that is multiplied by the power an engine makes if the conditions are not the same as the correction factors std conditions of pressure, humidity and temperature. This corrects the number to how much power it would make in theory if it were on a day when the pressure, humidity and temperature were at the actual standard conditions.
Because this number is a theoretical calculation as to how much difference the power will be changed by the different conditions there is a possibility for error. If there is error it is multiplied by the distance you are from the standard conditions. This is why the closer your correction factor is to zero the more accurate the number is. Unfortunately it can't always be zero so we do the best we can with correction factors. A correction factor that is not perfect will still be closer than no correction at all for the purposes of comparing your own data.