The editorial by Helena Espirito Santo, PhD, from the Instituto Superior Miguel Torga in Coimbra, Portugal, emphasizes the importance of reflecting on the validity of assessment instruments, particularly in the context of the Revista Portuguesa de Investigação em Ciências da Saúde (RPICS). The author suggests that authors should explicitly discuss the validity of their instruments in the Methods section of their articles. If the instrument is a previously studied one with the same format and characteristics, a reference is sufficient. However, if the instrument has been modified, additional information about the adaptation is necessary. For new instruments, the development process, reliability measures, pilot study results, and other credibility-enhancing details should be provided. The editorial then delves into the concepts of validity and reliability. Validity refers to the instrument's ability to measure what it intends to measure, encompassing construct validity, criterion validity, and content validity. Construct validity assesses the measurement of unoperationalized attributes, criterion validity predicts specific performance through independent measures, and content validity ensures the instrument represents a finite domain of behaviors. Reliability, or fidedignity, measures the instrument's consistency in providing similar results when used under the same conditions. Various methods to assess reliability include Cronbach's alpha, split-half reliability, Kuder and Richardson's formula, stratified Cronbach's alpha, and maximum likelihood reliability. Test-retest reliability and inter-rater reliability are also discussed, along with methods to evaluate measurement errors using ANOVA. In conclusion, the editorial underscores the importance of using valid and reliable instruments and the necessity of presenting psychometric analyses in RPICS articles.The editorial by Helena Espirito Santo, PhD, from the Instituto Superior Miguel Torga in Coimbra, Portugal, emphasizes the importance of reflecting on the validity of assessment instruments, particularly in the context of the Revista Portuguesa de Investigação em Ciências da Saúde (RPICS). The author suggests that authors should explicitly discuss the validity of their instruments in the Methods section of their articles. If the instrument is a previously studied one with the same format and characteristics, a reference is sufficient. However, if the instrument has been modified, additional information about the adaptation is necessary. For new instruments, the development process, reliability measures, pilot study results, and other credibility-enhancing details should be provided. The editorial then delves into the concepts of validity and reliability. Validity refers to the instrument's ability to measure what it intends to measure, encompassing construct validity, criterion validity, and content validity. Construct validity assesses the measurement of unoperationalized attributes, criterion validity predicts specific performance through independent measures, and content validity ensures the instrument represents a finite domain of behaviors. Reliability, or fidedignity, measures the instrument's consistency in providing similar results when used under the same conditions. Various methods to assess reliability include Cronbach's alpha, split-half reliability, Kuder and Richardson's formula, stratified Cronbach's alpha, and maximum likelihood reliability. Test-retest reliability and inter-rater reliability are also discussed, along with methods to evaluate measurement errors using ANOVA. In conclusion, the editorial underscores the importance of using valid and reliable instruments and the necessity of presenting psychometric analyses in RPICS articles.