Is the Bland-Altman plot method useful without inferences for accuracy, precision, and agreement?

ABSTRACT OBJECTIVE This study aims to propose a comprehensive alternative to the Bland-Altman plot method, addressing its limitations and providing a statistical framework for evaluating the equivalences of measurement techniques. This involves introducing an innovative three-step approach for assessing accuracy, precision, and agreement between techniques, which enhances objectivity in equivalence assessment. Additionally, the development of an R package that is easy to use enables researchers to efficiently analyze and interpret technique equivalences. METHODS Inferential statistics support for equivalence between measurement techniques was proposed in three nested tests. These were based on structural regressions with the goal to assess the equivalence of structural means (accuracy), the equivalence of structural variances (precision), and concordance with the structural bisector line (agreement in measurements obtained from the same subject), using analytical methods and robust approach by bootstrapping. To promote better understanding, graphical outputs following Bland and Altman's principles were also implemented. RESULTS The performance of this method was shown and confronted by five data sets from previously published articles that used Bland and Altman's method. One case demonstrated strict equivalence, three cases showed partial equivalence, and one showed poor equivalence. The developed R package containing open codes and data are available for free and with installation instructions at Harvard Dataverse at https://doi.org/10.7910/DVN/AGJPZH. CONCLUSION Although easy to communicate, the widely cited and applied Bland and Altman plot method is often misinterpreted, since it lacks suitable inferential statistical support. Common alternatives, such as Pearson's correlation or ordinal least-square linear regression, also fail to locate the weakness of each measurement technique. It may be possible to test whether two techniques have full equivalence by preserving graphical communication, in accordance with Bland and Altman's principles, but also adding robust and suitable inferential statistics. Decomposing equivalence into three features (accuracy, precision, and agreement) helps to locate the sources of the problem when fixing a new technique.

Depressão pós-parto e conflito conjugal: estudo longitudinal das associações bidirecionais em famílias de baixa renda / Postpartum depression and marital conflict: a longitudinal study of bidirectional associations in low-income families / Depresión posparto y conflicto marital: estudio longitudinal de las asociaciones bidireccionales en familias de bajos recursos

Com base em uma abordagem sistêmica, nosso objetivo é examinar longitudinalmente as associações bidirecionais entre depressão pós-parto e conflito conjugal durante os dois primeiros anos da criança e propor um método de análise de dados compatível com tal abordagem. Mães de baixa renda responderam à Escala de Depressão Pós-natal de Edinburgh e avaliaram o relacionamento com o parceiro. O modelo de equações estruturais não recursivo mostrou associações significativas no sentido da influência da DPP sobre o conflito conjugal. Relações bidirecionais significativas não foram encontradas entre as variáveis. A discussão centra-se no fato de termos encontrado maior probabilidade da DPP desencadear o conflito conjugal do que vice-versa....

Based on a systemic approach, our objective is to examine the bidirectional associations between postpartum depression (PPD) and marital conflict during the first two years of the child’s life, and to propose a method of data analysis compatible with this approach. Mothers were given the Brazilian version of the Edinburgh Postnatal Depression Scale and their marital relationship was evaluated. Using a non-recursive structural equation model significant associations were found in the direction of the influence of PPD on marital conflict. Bidirectional associations between the variables were not found. Discussion focuses on the higher probability of PPD leading to marital conflict than the other way around...

Basado en un abordaje sistémico, nuestro objetivo es examinar longitudinalmente las asociaciones bidireccionales entre depresión postparto y conflicto marital durante los primeros dos años de vida del infante y proponer un método de análisis de datos compatible con tal abordaje. Madres de bajos recursos respondieron a la Escala de Depresión Postparto de Edinburgh y evaluaron el relacionamiento con sus parejos. El modelo de equaciones estructurales no recursivo mostró asociaciones significativas en el sentido de la influencia de la depresión postparto sobre el conflicto marital. Relaciones bidireccionales significativas no fueron encontradas entre las variables. La discusión central es el hecho de que hayamos encontrado una mayor probabilidad de la depresión posparto desencadenar el conflicto conyugal que viceversa...

A presença de nitrito e nitrato na dieta diária de escolares do município de São Paulo, SP / The presence of nitrite and nitrate in the daily diet of students - São Paulo, SP

Nitrites and nitrates are substances naturally found in foods either from animal or vegetal source, and also in drinking water. Concern has repeatedly been expressed in the scientific and popular literature about the extent and effects of nitrate and nitrite in our diet. The aim of this study was to estimate the presence of nitrate and nitrite, in the daily diet food of students, applying a questionnaire form asking which of the 25 food items were eaten the day before (diet recall). The students attend from 1st to 8th grade in private or public schools in São Paulo city, State of São Paulo, Brazil (in all turns, with people from 6 to 25 years-old). 6,185 students filled the form and 5,991 informed complete dietary data...

Pain evaluation of patients with fibromyalgia, osteoarthritis, and low back pain

The purpose of this study was to evaluate and compare pain as reported by outpatients with fibromyalgia, osteoarthritis, and low back pain, in view of designing more adequate physical therapy treatment. PATIENTS AND METHODS: A Portuguese version of the McGill Pain Questionnaire - where subjects are asked to choose, from lists of pre-categorized words, one or none that best describes what they feel - was used to assess pain intensity and quality of 64 patients, of which 24 had fibromyalgia, 22 had osteoarthritis, and 18 had low back pain. The pre-categorized words were organized into 4 major classes -- sensory, affective, evaluative, and miscellaneous. RESULTS: Patients with fibromyalgia reported, comparatively, more intense pain through their choice of pain descriptors, both sensory and affective; they also chose a higher number of words from these classes than patients in the other groups and were the only ones to choose specific affective descriptors such as "vicious", "wretched", "exhausting", "blinding". CONCLUSION: Assuming that each disease presents unique qualities of pain experience, and that these can be pointed out by means of this questionnaire by patients' choice of specific groups of words, the findings suggest that fibromyalgia include not only a physical component, but also a psycho-emotional component, indicating that they require both emotional/affective and physical care