Inter-rater reliability refers to the extent to which a tool will consistently measure what it is supposed to measure no matter who is using the tool. The most important types of reliability are inter-rater reliability and test-retest reliability. Internal validity is important because it ensures that the study results are based on the specific causes in the study and not outside factors. Internal validity refers to the extent to which the results of a study are, in fact, a result of cause and effect. In other words, this determines if a study with a small sample of adult females ages 18 to 24 who are left-handed can be generalized to all females within the ages of 18 to 24 who are left-handed. Types of ValidityĮxternal validity refers to the extent to which the results of a study can be generalized to the greater population. There are two main types of validity in research: external validity and internal validity. The two concepts are related but not interchangeable. Additionally, it can be valid but not reliable. It is important to note that a measurement tool or research study can be reliable but not valid. It is reliable because time after time, it will give the same result in either pounds or inches. If the study is replicated over and over with sustainable results, it is deemed reliable.Īn example of reliability in the form of a tool would be a bathroom scale or measuring tape. The same can be applied to a research study. In other words, a tool is reliable if you use it over and over and consistently get the same results. Reliability often refers to repeatability. An intelligence test says it measures IQ, and in fact it has been proven to actually measure IQ. An example of validity would be an intelligence test. Additionally, the validity of a study refers to the extent to which the study is actually studying what it says it is studying. Validity refers to the extent to which a tool measures what it is supposed to measure. It is important to understand that there is a difference between reliability and validity. You may also determine if a measurement tool is both valid and reliable. These terms are generally used within the field of statistics and refer to forms or types of measurement. Distinguish Between Validity and Reliability Researchers often question whether or not the outcomes or findings of a study are valid. Essentially, one would determine if the results of a study or outcomes are factually sound, or valid. In research, validity often refers to results or an outcome. For example, you may ask if a position is valid, based on facts or logical. You may use the term validity to refer to someone’s position or opinion on a certain subject. On the other hand, the word validity refers to the quality of being logically or factually sound.