Perhaps in the mid-tones you might find a rough equivalence, but as far as the highlights and shadows are concerned, the algorithm in Lightroom tries to prevent blowing out the highlights and prevent losing all the detail in the shadows, so most likely the equivalence between camera and Lightroom does not hold for shadows and highlights.
You could switch to Process Version 2010 as the sliders are not as "ADAPTIVE" as they are in PV 2012 for the highlights and shadows when using the Exposure slider.
Even there, the camera sensor reacts to light differently than whatever the exposure algorithm is in Lightroom. We know that the camera sensor (and film too) react to light according to an S-shaped curve, and while Adobe doesn't say exactly what its exposure algorithm is, I'm pretty darn sure it doesn't do the same things as your camera sensor.
So, to answer the original question, there are going to be differences between a 1-stop change in exposure in the camera, and a 1-stop change in Lightroom.
Pretty clear, if definitive values are important, don't rely on LR
Exposure. I'll now do this in Photoshop, convert to Lab color, which allows
eye dropper to sample luminance. I'll begin with a series of exposures
running through each aperture, sample one spot across all exposures and
noting shift in luminance. I can then compare the progression in luminance
values to stops, see if the relationship is linear, establish whatever
sliding scale. Then locking settings across all exposures and only varying
the strobe values, I can study the changes and convert back to stops. Valid?
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