Reliability: 4 Types & Examples

During the process of conducting research and data collection, two important concepts are considered crucial: validity and the other is reliability. These concepts maintain the veracity of the findings of research. It is because of these factors that meaningful and trustworthy conclusions are drawn. So let’s discuss the concept of reliability.

Reliability

It refers to the consistency and trustworthiness of the information collection process. In other words, reliability in research tests whether the same results are obtained or not after using the same instrument more than once. A specified measure, such as a questionnaire, is thought to be reliable if the same results are produced after its application many times. It indicates that if independent experiments are conducted by different researchers and the same results are produced from those experiments,

For example, a person wants to check if the battery of a smartphone is reliable or not. For this he or she should fully charge the battery for more than one time under the same conditions. The conditions may be the same in terms of the same brightness level, the same patterns, and the same apps running.

If the same performance is shown by the battery in different situations, then it is said that the battery of the smartphone is reliable.

Assessment of reliability in research

The assessment is made by performing a task many times or in many ways. In one situation, one aspect is used, while in another situation, another aspect is used to keep control of the research. For instance, one can use the same test on different people or different tests on the same people. In both situations, one element is held constant. While other elements are changed to ensure that other factors have no influence on the results of the research.

Types of Reliability in Research

Different types of reliability in research are used depending upon the research types. The four types of reliability in research are discussed below.

Test-retest reliability

In test-rest reliability, the same test is given to the same group of people more than once. If the results of each occasion are the same from this method of test-retest reliability, then we say that the test is reliable and that external factors have no effect on it.

To conduct a test to check the test-retest reliability, the following guidelines need to be followed:

The method of research should be consistent.

A sample group should be created where the members are consistent

The chosen method is used for administration of the test

The same testing process is repeated numerous times with the same group of samples.

Examples

1. A group of students is surveyed regarding their satisfaction with the school’s parking on Monday and later again on Friday. Then compare the results to see whether they are consistent or not.
2. The consistency of responses of the employees of any company regarding their job satisfaction can be checked by giving the same questionnaire at one time and then again a week later. Then the results can be compared, and the consistency of the results can be checked.
3. Another example is checking the shopping habits and preferences of people through conducting surveys. If the responses of the people do not change over time, it will indicate that the results are reliable due to the test-retest reliability method.

Parallel forms reliability

In parallel forms of reliability, the same group of people are given different types of tests. It is to be determined whether the same results are produced with these different methods. If the results of parallel forms reliability are the same, then we say that there is consistency of results. In other words, the parallel-forms reliability method is successful. On the other hand, if the results are different from these different methods, then the parallel forms reliability is not successful. To make the parallel forms reliable, it is important that:

There is same required information in each method

The same behavior patterns are displayed by the group of participants for each test

Examples

1. An interview can be conducted with the customers regarding a new product, then they may be observed while using the product, and then a survey can be conducted about the ease of use of the said product. After the survey, the results can be compared.
2. The satisfaction level of the employees of a company can be assessed through a questionnaire, interview, and focus group discussion, and then the results of different tools can be compared to check for consistency in results.
3. In the example of checking the shopping behaviors and preferences of the customers, the information is obtained several times. The same information can be cross-checked through the sales information at the mall. Then the results are compared for consistency.

Inter-rater reliability

In the inter-rater reliability method, different researchers are in the same group, and then the results obtained by different researchers are compared with each other.  This inter-rater reliability method helps in avoiding the influencing factors regarding each assessor researcher. The factors may be personal bias, researchers’ mood, human error, etc.

If the results obtained by different researchers are similar, then the inter-rater reliability method is considered consistent and the researchers have collected the same data from the group. Different methods can be used, such as observations, interviews, and surveys.

Examples

1. The group of children who are playing can be checked by different behavioral specialists to check their level of social and emotional development. Then their results can be compared with each other to check for consistency.
2. Similarly, the satisfaction level of the employees of a company can be assessed through the use of the observation method by different researchers. At the end, the results obtained by different researchers are compared for consistency.
3. Suppose that consumers with shopping preferences are tested independently by different assessors by employing different techniques such as surveys, interviews, and analyzing the data collected from the mall. If these assessors obtain the same results, leading to similar conclusions, then we say that the inter-rater reliability method used is consistent.

Internal consistency reliability

In internal consistency reliability, the internal consistency is checked between the internal research methods or parts of the research methods to ensure that the same results are found or not. This determination is made in two typical ways.

Split-half reliability test:

In a split-half test, the research method of the test, such as a survey, is split into two halves, and each half is delivered separately to a small group. After that, the results of both halves are compared with each other. In cases of consistent results, the results of the method are considered reliable.

Inter-item reliability test:

In an inter-item test, the researcher administers sample groups numerous times with parallel form testing and then finds the correlation between the results of each method. One can calculate the average and fix a number to determine whether the results are reliable or not.

Examples 

1. A company’s cleaning department can be given a questionnaire regarding which cleaning products work best. The questionnaire is split into two halves, and each half is given separately. Then the correlation is found among the two halves.

Later on, the members are interviewed and observed to check which products are most used by the staff and which people like the best. Then one can calculate the correlation between the responses, and the average is calculated for finding the inter-item form.

1. Taking the example of the shopping preferences of consumers, the researcher will divide the focus in half and independently analyze each half. This splitting will provide two subgroups with identical qualities, and they can be viewed as the same construct. If the results are correlated, the research will be considered consistent.

Coefficient of reliability

The reliability coefficient is introduced to measure the accuracy of the measurement of a specific object. It is defined as whether a test is reliable, repeatable, or not. The value of the coefficient lies between 0 and 1.00. 0 indicates no reliability, while 1 shows perfect reliability.

The coefficient R is used with the formula R = (N/(N-1)) * (Total Variance – Sum of Variance)/Total Variance.

N shows how many times the test has been run. The value of R=0.80 indicates sufficient reliability.