I feel stupid about asking this...

[Inevitability]

But how do CR-increasing templates interact with very weak monsters? For example, let's take a Ghost raven. A raven has CR 1/6. Ghost adds +5 to that.

Would the result be:

1. A CR of 5.166666666? This seems to be the answer from strict reading of the rules, but doesn't make sense.

2. A CR of 2? The 1/6th CR a raven has is increased by five 'steps'; first to 1/4th, then to 1/3rd, etc.

[Segev]

Technically the first. Which means that 5 CR 1/6 ravens plus 1 CR 5 1/6 ghost raven would be a CR 6 encounter.

If you're combining ghost ravens, the 1/6 gets overwhelmed by the additive properties of multiple CR 5s, and are not worth considering. So unless you're combining with other sub-CR-1 critters, treat it as CR 5 for any calculations. It'll save you a headache and not result in any significant change to the final encounter values.