In research, to make observations for various variables, that is, the primary data that are collected, recorded, analyzed and interpreted special tools are developed. These tools are referred to as instruments and the systematic procedure for the selection and development of these tools is known as instrumentation (Pangaro and Shea, 2015).
Instrumentation includes all those measures which are used during the research to collect data. The quality of research depends to a large extent on the quality of the research instrument. The more efficient the research instrument, the more authentic the research becomes. The two most common instruments used in nutritional research include questionnaires (surveys, interviews) and experimental …show more content…
It can be referred to as the ability of a research design to provide an adequate test of a hypothesis. For example, a researcher decides that a particular medication prevents the development of heart disease as the participants who took the medication developed lower rates of heart disease than did those who never took the medication. This interpretation of the study’s results can be correct, if the study has high internal validity for which the researcher would have to perform an experimental study which should contain an experimental as well as a control group. …show more content…
Over the course of time participants naturally change. This may bring about changes in the participants during the experiment which is not because of the treatment.
Testing
The third threat to the internal validity is ‘testing’. Taking a test generally affects subsequent testing; thus, participants’ performance at the end of the study may differ from an initial testing, not because of treatment but because they are familiar with the measure.
Instrumentation
The fourth threat to internal validity is ‘instrumentation’. Over the period of time, there may be some changes in the instruments. Thus the change in the participants may occur due to this change in the instruments rather than due to the treatment.
Regression
The fifth threat to the internal validity is ‘regression’. When the participants are selected on the basis of extreme scores (low and high), as these scores are closer to the mean when they are
Subject selection biases
The sixth threat to the internal validity is ‘subject selection biases’. When the participants of the study design are unequal in relevant variables, they cannot be assigned to the treatment groups. This threat occurs to both the cross-sectional as well as the longitudinal