Reliability

What does “reliability” of study mean?
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What does “validity” of study mean?

At the biginning, these terms were developed for use in quantitativesocial science, according Easterby-Smith who mention that there has been some reluctance to apply these terms to phenomenological research because of they could imply acceptance of one absolutereality.

In relation to the definitions, there are substancial divergencies among different authors. Some of them have given the followings definitions:
Reliability
Yin- Reliability demonstratesthat the operation of a study, can be repeated with the some results.

Bell- Reliability is the extent to which a test or procedure produces similar results under constant conditions on allocassions.

Sapsford and Evans- Reliability is a term used of measuring instruments, including the human observer.

Easterby-Smith- Reliability refers to the extend to which your data collection techniquesor analysis procedures will yield consistent findings.

The following questions are used to assess:
a) Will the measures yield the same results on other occasions?
b) Will similarobservations be reached by other observers?
c) Is there transparency in how sense was made from the raw data?

Validity
Basically, this concept is used to judge if the research accurately describes thephenomenon which it is intent to describe.

Sapsford and Evans – Validity is the extent to which an indicator is a measure of what the researcher wishes to measure.

Bell – If an ítem isunreliable, so it must also lack validity, but however a reliable ítem is not necessarily also valid.

Some threats to validity are:

History – In order to know the level of satisfaction of the middleclass in Argentina with respect to private health system, we should not do research during the time the goverment is prepearing election because they invest in the public health system in this period....