Abstract Paper aims In this study, effective strategies to combine and select forecasting methods are proposed. In the selection strategy, the best performing forecasting method from a pool of methods is selected based on its accuracy, whereas the combination strategies are based on the mean methods’ outputs and on the methods’ accuracy. Originality Despite the large amount of work in this area, the actual literature lacks of selection and combination strategies of forecasting methods for dealing with intermittent time series. Research method The included forecasting methods are state-of-the-art approaches applied to industrial and academics forecasting problems. Experiments were performed to evaluate the performance of the proposed strategies using a spare part data set of an industry of elevators and a data set from the M3-Competition. Main findings The results show that, in most cases, the accuracy of the demand forecasts can be improved when using the proposed selection and combination strategies. Implications for theory and practice The proposed methodology can be applied to forecasting problems, covering a variety of characteristics (e.g., intermittency, trend). The results reveal that combination strategies have potential application, perform better than state-of-the-art models, and have comparable accuracy in intermittent series. Thus, they can be employed to improve production planning activities.

RESUMO OBJETIVO Mesmo que o estresse seja conhecido há muito tempo como um fator provocativo para a doença de Graves, sua relação com a tireoidite de Hashimoto é mais controversa. Estudos sobre esse tema são escassos. O objetivo deste artigo é relatar um caso de Hashitoxicose induzida por estresse. RESULTADOS Aqui nós relatamos um caso de Hashitoxicose induzido por um evento psicológico estressante em uma mulher de 28 anos com tireoidite de Hashimoto. Ela permaneceu estável eutireoidiana por 12 anos. Ela veio a nossa observação pela primeira vez em abril de 2016, enquanto eutireoidiana. Voltou após 11 meses por causa de fadiga e palpitações, na ausência de dor no pescoço. Testes de função tireoidiana revelaram uma tireotoxicose moderada (TSH indetectável; T4F 36,94 pmol/L, valores normais 9,0-24,46; FT3 13,50 pmol/L, valores normais 3,07-6,14) com anticorpos negativos para o receptor de TSH. Nos últimos três meses ela experimentou um evento psicológico estressante. Os marcadores inflamatórios foram negativos e a contagem de leucócitos foi normal. A ultrassonografia da tireoide revelou um aumento modesto da vascularização. Hipotireoidismo subclínico transitório ocorreu após sete semanas e se recuperou espontaneamente. Na última visita, a paciente ainda estava em eutireoidismo. (TSH 1,01 mU/L; FT4 9,22 pmol/L; FT3 3,98 pmol/L). Também realizamos a sorotipagem e a genotipização do HLA. CONCLUSÃO Este caso demonstra que, similarmente à doença de Graves, também a Hashitoxicose pode ser desencadeada por eventos estressantes da vida.

SUMMARY OBJECTIVE Even though stress has been long known as a provocative factor for Graves’ disease, its relationship with Hashimoto's thyroiditis is more controversial. Studies on this topic are scanty. This paper aims to report a case of stress-induced Hashitoxicosis. RESULTS Here we report a case of Hashitoxicosis induced by a psychological stressful event in a 28-year-old woman with Hashimoto's thyroiditis. She had remained stably euthyroid for 12 years. She was first observed in April 2016, while euthyroid. She came back after 11 months because of fatigue and palpitations, in the absence of neck pain. Thyroid function tests revealed moderate thyrotoxicosis (undetectable TSH; FT4 36.94 pmol/L, normal values 9.0-24.46; FT3 13.50 pmol/L, normal values 3.07-6.14) with negative TSH-receptor antibodies. In the previous three months, she had experienced a psychological stressful event. Inflammatory markers were negative, and the white cell count was normal. Thyroid ultrasound revealed a modest increase in vascularization. Transient subclinical hypothyroidism ensued after seven weeks and spontaneously recovered. On the last visit, the patient was still on euthyroidism. (TSH 1.01 mU/L; FT4 9.22 pmol/L; FT3 3.98 pmol/L). We also performed HLA serotyping and genotyping. CONCLUSION This case demonstrates that, similarly to Graves’ disease, Hashitoxicosis can also be triggered by stressful life events.