Clear and consistent naming

[baogorek]

Perhaps we could use this issue to solidify the names of all the major concepts.

• I think loss_matrix calibration.py and reweight.py should actually be called something like metrics_matrix.
• noise_level is about changing the starting value, so maybe something like perturbation_log_sd

That's all I have right now.

[nikhilwoodruff]

I do actually prefer noise_level since it seems cleaner? And it is accurate.

Agree on loss_matrix, but how about estimate_matrix instead?

[baogorek]

noise_level is fine. It's accurate. The documentation will clear up any ambiguity.

The only thing about estimate_matrix is that we'll have individual household level metrics in there. Is the number of children between 10 and 14 in household #119 an estimate? Technically, yes. But since there is more or less raw data in here, I'd be more likely to refer to it as a "data matrix," "metrics matrix" or something along that vain. But I'm fine with it either way.