... research quality and therefore, four commonly used tests namely construct validity, internal validity, external validity and reliability are proposed when establishing the quality standard of ... increase quality standards when conducting case study research Table 2.4: Case study tactics for four design tests Tests Construct Validity Internal Validity External Validity Reliability Case Study ... conclusions were then drawn based on the findings 2.7 Reliability and validity When conducting scientific research, validity and reliability are two important factors that determine the trustworthiness...