Human Impact: HI:2.0.2 value definitions and DT_HI:1.0.0 disagree in four cells

[sandakelum97]

While implementing the deployer decision model I noticed that the two representations of Human Impact on the reference page appear to differ. I'd like to know which is normative.

The ssvc:HI:2.0.2 value definitions and the generated decision table ssvc:DT_HI:1.0.0 give different results for these combinations:

Safety Impact	Mission Impact	HI:2.0.2 definitions	DT_HI:1.0.0
Marginal	Degraded	Medium	Low
Marginal	MEF Support Crippled	Medium	Low
Marginal	MEF Failure	High	Medium
Critical	Degraded	High	Medium
Critical	MEF Failure	no matching condition	High

The last row appears to be undefined in the prose. Low requires Safety Negligible. Medium requires (Negligible AND MEF Failure) or (Marginal AND Degraded/Crippled). High requires (Critical AND Degraded/Crippled) or (Marginal AND MEF Failure). Very High requires Catastrophic or Mission Failure. Safety Critical with Mission MEF Failure satisfies none of these.

I checked the Dryad calculator's standalone Human Impact model and it agrees with the decision table in all four cases.

One consequence, if the decision table is normative: Safety Impact Marginal produces the same Human Impact as Negligible for every Mission Impact value, so the four-value decision point behaves as three values for deployers. I wanted to check whether that is intended.

Which representation should implementers follow?

[sei-vsarvepalli]

@sandakelum97 - there is a related issue #1218 - your observation is right. The prose language needs an update.