2.4.2.1 Reliability: Internal consistency and Test-retest reliability
To measure the internal consistency, Cronbach-α values per dimensions were calculated and also a total Cronbach-α value was computed. Cronbach-α with values of 0.60 to 0.80 is regarded as evidence of good reliability and those above 0.80 indicating excellent reliability.17, 18 The parent and teens reports Tr-PedsQL™ 3.0 EoE module were applied for twice at one week interval. Test-retest reliability was determined by using the intraclass correlation coefficient (ICC). ICCs with values of 0.60 to 0.80 regarded as evidence of good reliability and those above 0.80 indicating excellent reliability.17