• Allen M. Khakshooy
  • Francesco Chiappelli


In the next leg of our “three-legged” stool, we learn that the research methodology is much more than just a simple set of methods—it is the science of measurement and the process of obtaining and allocating the sample. Methodology also critically evaluates the overall validity and reliability of scientific research. We ask questions like how the researchers obtain their information and why they use a particular technique, tool, or protocol.


Population Sample Simple random sampling Systematic sample Stratified sampling Cluster sampling Researcher-completed instruments Subject-completed instruments Construct validity Content validity Criterion validity Reliable instrument Inter-rater reliability Intra-rater reliability Generalizability (G) theory Data Quantitative data Qualitative data Variable Continuous variable Discrete variable Interval measures Ratio measures Categorical variable Nominal measure Dichotomous measure Ordinal measure 

Supplementary material

Video 1

Variables. Reprint courtesy of International Business Machines Corporation, © International Business Machines Corporation (MOV 108085 kb)

Recommended Reading

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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Allen M. Khakshooy
    • 1
  • Francesco Chiappelli
    • 2
  1. 1.Rappaport Faculty of MedicineTechnion-Israel Institute of TechnologyHaifaIsrael
  2. 2.UCLA School of DentistryLos AngelesUSA

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