Concept of Reliability – In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for bringing about a certain goal, like acquiring knowledge or verifying knowledge claims. This normally involves various steps, like choosing a sample, collecting data from this sample, and interpreting the data. The study of methods concerns a detailed description and analysis of these processes. It includes evaluative aspects by comparing different methods.
In this way, their benefits and drawbacks are evaluated, as well as the research goals for which they may be used. These descriptions and evaluations are predicated on philosophical background assumptions; examples include how to conceptualize the phenomena under study and what constitutes evidence in favor of or against them. In its broadest sense, methodology encompasses the discussion of these more abstract issues.
Concept of Reliability
Reliability in statistics and psychometrics is the overall consistency of a measure. A measure is said to have a high reliability if it produces similar results under consistent conditions. “It is the characteristic of a set of test scores that relates to the amount of random error from the measurement process that might be embedded in the scores. Scores that are highly reliable are accurate, reproducible, and consistent from one testing occasion to another.
Definition of Reliability:
According to Chris Jordan
“Reliability is the consistency of set of measurements or measuring instrument often used to describe a test”
According to Houghton
“Reliability is an attribute of any system that consistently produces the same results, preferably meeting or exceeding its specifications”
According to Livingstone
“Reliability is the ability of an item to perform a required function under stated conditions for a specified period of time”
(Ref by-Seenidurai Paulraj/Introduction to Nursing Research/ 106)
Classification of Reliability:
There are four general classes of reliability estimates, each of which estimates reliability in a different way. They are:
1. Inter-Rater or Inter-Observer Reliability: Used to assess the degree to which different raters/observers give consistent estimates of the same phenomenon.
2. Test-Retest Reliability: Used to assess the consistency of a measure from one time to another.
3. Parallel-Forms Reliability: Used to assess the consistency of the results of two tests constructed in the same way from the same content domain.
4. Internal Consistency Reliability: Used to assess the consistency of results across items within a test
(Ref by- Seenidurai Paulraj/Introduction to Nursing Research/1/106)
Difference between Validity and Reliability
| Characteristics | Reliability |
| Definition | It is the measure of degree to which the same measure gives consistent results upon repeated application. |
| Nature of error indicated | Indicates chance error or random error.. |
| Importance | Importance of validity of findings i.e. it is a constituent of validity |
| Types |
|
| Influencing factors or sources of errors needing attention | Subjects, characteristics being measured, observers, situations, instruments, processing. |
(Ref by-Sadeka Tahera Khanom/Research Methodology/2nd/89)
Factors Influence/ Resulting Poor Reliability
1. Change in the characteristic that is being measured (e.g. blood pressure normally fluctuates from time to time).
2. Language of or change in the measuring instrument (e.g. defective measuring instrument or when the question is worded in a way that it is liable to different interpretations by different individuals).
3. Inconsistency of the observer (e.g. when the interviewer does not use same criteria for classification of variables. This is possible when no guide line is provided for recording answers, or when interviewer lacks correct knowledge or is not careful enough or when operational definitions are not provided.
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