Understanding and Using the Term 'Bias' in Measurements: Explained by Experts

[ChrisVer]

I don't know if it's the best place to ask this, but oh well... how to use the term "bias"?
What is the meaning of bias? I always thought that biasing a measurement meant something like "enforcing" some of its results, as for example predetermining what you want to get and so biasing it...
However I read a phrase like this:
"The largest deviation is found in the transition region between the electromagnetic (EM) barrel and endcap. This is due to clusters reconstructed in poorly instrumented regions of the calorimeters which tend to have underestimated energies, and may lead to a bias in the τh pseudorapidity value."
--Determination of the tau energy scale and the associated systematic uncertainty in proton-proton collisions at √ s = 8 TeV with the ATLAS detector at the LHC in 2012
Does the bold phrase make sense?

 

[mathman]

Bias usually refers to some sort of effect which leads to a systematic error in the results, in contrast to a random error.

 

[dukwon]

In this case it means there is an effect (poor instrumentation) that is causing a distribution of a variable (pseudorapidity) to shaped differently to how it is. An unbiased detector has a efficiency that is flat across its whole range.

 

[ohwilleke]

More specifically, bias is a systemic error that tends to cause a result in one direction, rather than a systemic error whose effect is random in direction.