This involves the efforts to establish where there observations are consistent with the others, example a study involving the interview of two individuals then there is a need to compare the two observations and establish whether the results from both observations are consistent and therefore reliable.
In test reliability we try to establish the correlation between studies undertaken in two time periods, it is evident from research that given the same sample and undertake the study tafter a short time period then the higher the correlation but if we took the same sample and the have a longer time period then the lower the correlation.
This involves testing reliability using many set of questions that tend to yield same results, in a study questions can be split into two where the second part tends to establish the same results as the first part, this way the similarities will help establish whether the results are consistent and reliable.
This involves establishing a single measure of consistence on a group of participants at the same time and try to establish whether the results are consistent, this helps in determining whether a study undertaken on the group will be consistent.
All the above methods are used in establishing whether the results of a study are reliable or not, however the methods have their strength and weakness but they are important in determining reliability.
The validity can be defined as the best approximation of truth of an inference, however the validity of a study does not depend on the use of good study design or even use of good samples in the study. Validity measure is divided into four including conclusion validity, internal validity, construction validity and finally external validity.
Conclusion validity involves comparing the results of the study and the conclusion, for example if in a study we want to establish the relationship that exits between variable A and B and that A causes B then if we conclude that A causes B then the results are valid.
In this form of validity we establish whether the relationship between variables is causal, example if we establish that A and B are related in a study we test whether A causes B and this is achieved through tests.
This validation method tend to establish whether the relationship being established is credible, this is done through determining whether the measures that were intended to be measured were measured, this can only be achieved if the study construction was well prepared for the collection of observations.
This tends to establish that a study is valid if same results can be achieved using another sample or if the study was undertaken at different area or different time period, this is what is referred to as external validity. Therefore All the above validity methods will help establish whether a research proposition or inference is valid or not valid.
validity and reliability: