Are the spell attack rolls from unchained really "the same"?

[villadelfia]

The book pretty explicitly states that the system should not change any of the statistics behind spell saves, only the math.

However, the book makes a math error, here is a quote from the book: Normally, the orc would attempt a DC 15 Will saving throw (10 + 1 for a 1st-level spell + 4 for the wizard's Intelligence bonus). Since the orc's Will save modifier is –1, he has to roll a 16 to succeed, and thus will fail his save 80% of the time.

Rolling at least 16 to succeed doesn't correspond to a 20% chance of success. Simply counting the numbers that lead to a success will tell you that it should be 25% (and thus 75% fail chance). The numbers to succeed are: [16, 17, 18, 19, 20], that's 5 numbers, x5% = 25%.

The next part is actually correct, the wizard has a 20% chance of failure (which means success from the point of view of the orc). This means the chances have shifted 5% in favor of the wizard unlike the book states.

Here is a chart to make everything more clear: http://i.imgur.com/DQgZPbJ.png

Note that when a roll ties with the DC, the roller wins. When the orc rolls that means he does not get affected by the spell. When the wizard rolls that means he does affect the orc with the spell.

[kestral287]

It's due to your last line.

Either shift the numbers by one in favor of the Orc or flip the general rule so that for the purposes of saves, the defender wins ties. Solves the problem.

[CrackedOzy]

There's a simple solution here, make the DC to hit with the spell attack roll (12 + Save) instead.

[Bandw2]

yeah this is due to the rollee winning ties, either make an exception or instead make it +12.

[Can'tFindthePath]

Bandw2 wrote:

yeah this is due to the rollee winning ties, either make an exception or instead make it +12.

Huh. Sure enough, the DC should be 12 + Save modifier. It seems so unintuitive that the base assumption (10 + x) should move 2 points instead of 1, but that is how it is.

[Bandw2]

Can'tFindthePath wrote:

Bandw2 wrote:

yeah this is due to the rollee winning ties, either make an exception or instead make it +12.

Huh. Sure enough, the DC should be 12 + Save modifier. It seems so unintuitive that the base assumption (10 + x) should move 2 points instead of 1, but that is how it is.

well it's because it gets moved one simply from the flip and then the rollee always winning thing moves it an additional spot away.

if the roll was an odd number we wouldn't have this issue for instance.

[Vinret]

Did Paizo react at this in some way?