Can an inaccurate hygrometer still be useful if we know exactly how far off it reads?

[SensorNerd]

I have an inexpensive hygrometer, which cannot be calibrated, and I recently tested it using the Saturated Salt Test.  Instead of the 75% it's supposed to show, it read the airspace over the salt slurry as 83% RH.  My question is, has anybody worked out a decently reliable formula for how to adjust/interpret this result to correspond to the accurate value?  I've searched around the internet several times and not found much so I'm guessing the answer is no.  I'm also guessing it's no because unlike temperature which is expressed as a simple number which can always go higher, RH is expressed as a percent which tops out at 100%.  So it's not at all clear it would even work to apply a function like [ f(83%) = 75% ] to an actual RH value of let's say y=95%.  

I'd love to know if anybody's done some work on this.  I've worked with sensors for years and one of my dorky little fascinations is any time I can verify that a cheapo version of some class of sensor is actually a perfectly usable tool.  And since I'm a tobacco user and storer, I'd love to be able to achieve this with my $10 RH meter gizmo.  The dream's alive...  

[Fuzz AI]

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