Marco Túlio de Freitas Ribeiro

Why Should I Trust You?: Explaining the Predictions of Any Classifier

Despite widespread adoption, machine learning models remain mostly black boxes. Understanding the reasons behind predictions is, however, quite important in assessing trust, which is fundamental if one plans to take action based on a prediction, or when choosing whether to deploy a new model. Such understanding also provides insights into the model, which can be used to transform an untrustworthy model or prediction into a trustworthy one. In this work, we propose LIME, a novel explanation technique that explains the predictions of any classifier in an interpretable and faithful manner, by learning an interpretable model locally varound the prediction. We also propose a method to explain models by presenting representative individual predictions and their explanations in a non-redundant way, framing the task as a submodular optimization problem. We demonstrate the flexibility of these methods by explaining different models for text (e.g. random forests) and image classification (e.g. neural networks). We show the utility of explanations via novel experiments, both simulated and with human subjects, on various scenarios that require trust: deciding if one should trust a prediction, choosing between models, improving an untrustworthy classifier, and identifying why a classifier should not be trusted.

Pareto-efficient hybridization for multi-objective recommender systems

Performing accurate suggestions is an objective of paramount importance for effective recommender systems. Other important and increasingly evident objectives are novelty and diversity, which are achieved by recommender systems that are able to suggest diversified items not easily discovered by the users. Different recommendation algorithms have particular strengths and weaknesses when it comes to each of these objectives, motivating the construction of hybrid approaches. However, most of these approaches only focus on optimizing accuracy, with no regard for novelty and diversity. The problem of combining recommendation algorithms grows significantly harder when multiple objectives are considered simultaneously. For instance, devising multi-objective recommender systems that suggest items that are simultaneously accurate, novel and diversified may lead to a conflicting-objective problem, where the attempt to improve an objective further may result in worsening other competing objectives. In this paper we propose a hybrid recommendation approach that combines existing algorithms which differ in their level of accuracy, novelty and diversity. We employ an evolutionary search for hybrids following the Strength Pareto approach, which isolates hybrids that are not dominated by others (i.e., the so called Pareto frontier). Experimental results on two recommendation scenarios show that: (i) we can combine recommendation algorithms in order to improve an objective without significantly hurting other objectives, and (ii) we allow for adjusting the compromise between accuracy, diversity and novelty, so that the recommendation emphasis can be adjusted dynamically according to the needs of different users.

Perfil dos cuidadores de idosos nas instituições de longa permanência de Belo Horizonte, MG

The purpose of this cross-sectional study was to determine the profile of caregivers of elderly in long-term care facilities. The studied population included 181 randomly selected caregivers, 98 from philanthropic and 83 from private institutions in the city of Belo Horizonte. Data were collected applying structured questionnaires. The variables evaluated were sex, age group, educational level, marital status, income, economic condition, time of work in the facility, and professional experience. The data were compared using Chi-square and Fishers exact tests. There was no statistically significant difference between caregivers from the two facilities with regard to sex (p=0.62) and income (0.77). In the philanthropic facilities we observed more caregivers aged 50 years or more, widowers, with less than 4 years of study, socio-economic level D and who were working as caregivers in the facility for more than two years (p<0,05). The results of this study are relevant for discussing developing and implementing public policies aimed at qualifying the caregivers in long-term care institutions for elderly in Belo Horizonte.

Multiobjective Pareto-Efficient Approaches for Recommender Systems

Recommender systems are quickly becoming ubiquitous in applications such as e-commerce, social media channels, and content providers, among others, acting as an enabling mechanism designed to overcome the information overload problem by improving browsing and consumption experience. A typical task in many recommender systems is to output a ranked list of items, so that items placed higher in the rank are more likely to be interesting to the users. Interestingness measures include how accurate, novel, and diverse are the suggested items, and the objective is usually to produce ranked lists optimizing one of these measures. Suggesting items that are simultaneously accurate, novel, and diverse is much more challenging, since this may lead to a conflicting-objective problem, in which the attempt to improve a measure further may result in worsening other measures. In this article, we propose new approaches for multiobjective recommender systems based on the concept of Pareto efficiency—a state achieved when the system is devised in the most efficient manner in the sense that there is no way to improve one of the objectives without making any other objective worse off. Given that existing multiobjective recommendation algorithms differ in their level of accuracy, diversity, and novelty, we exploit the Pareto-efficiency concept in two distinct manners: (i) the aggregation of ranked lists produced by existing algorithms into a single one, which we call Pareto-efficient ranking, and (ii) the weighted combination of existing algorithms resulting in a hybrid one, which we call Pareto-efficient hybridization. Our evaluation involves two real application scenarios: music recommendation with implicit feedback (i.e., Last.fm) and movie recommendation with explicit feedback (i.e., MovieLens). We show that the proposed Pareto-efficient approaches are effective in suggesting items that are likely to be simultaneously accurate, diverse, and novel. We discuss scenarios where the system achieves high levels of diversity and novelty without compromising its accuracy. Further, comparison against multiobjective baselines reveals improvements in terms of accuracy (from 10.4% to 10.9%), novelty (from 5.7% to 7.5%), and diversity (from 1.6% to 4.2%).

Edentulism and shortened dental arch in Brazilian elderly from the National Survey of Oral Health 2003

OBJECTIVE To describe the distribution of edentulism and estimate the prevalence of functional dentition and shortened dental arch among elderly population. METHODS A population-based epidemiological study was carried out with a sample of 5,349 respondents aged 65 to 74 years obtained from the 2002 and 2003 Brazilian Ministry of Health/Division of Oral Health survey database. The following variables were studied: gender; macroregion of residence; missing teeth; percentage that met the World Health Organization goal for oral health in the age group 65 to 74 years (50% having at least 20 natural teeth); presence of shortened dental arch; number of posterior occluding pairs of teeth. The Chi-square test assessed the association between categorical variables. The Kruskal-Wallis and Mann-Whitney tests were used to assess differences of mean between number of posterior occluding pairs teeth, macro-region and gender. RESULTS The elderly population had an average of 5.49 teeth (SD: 7.93) with a median of 0. The proportion of completely edentulous respondents was 54.7%. Complete edentulism was 18.2% in the upper arch and 1.9% in the lower arch. The World Health Organization goal was achieved in 10% of all respondents studied. However, only 2.7% had acceptable masticatory function and aesthetics (having at least shortened dental arch) and a mean number of posterior occluding pairs of 6.94 (SD=2.97). There were significant differences of the percentage of respondents that met the World Health Organization goal and presence of shortened dental arch between men and women. There were differences in shortened dental arch between macroregions. CONCLUSIONS The Brazilian epidemiological oral health survey showed high rate of edentulism and low rate of shortened dental arch in the elderly population studied, thus suggesting significant functional and aesthetic impairment in all Brazilian macroregions especially among women.OBJETIVO: Descrever a distribuicao de edentulismo e estimar a prevalencia de denticao funcional e arco dentario reduzido entre idosos. METODOS: Estudo epidemiologico populacional com 5.349 individuos de 65 a 74 anos do banco de dados do inquerito nacional de saude bucal do Ministerio da Saude/Coordenacao Nacional de Saude Bucal em 2002 e 2003. Foram avaliados perda dentaria; cumprimento a meta da Organizacao Mundial da Saude para a faixa etaria (50% com pelo menos 20 dentes); presenca de arco dental reduzido, numero de pares em oclusao posterior; sexo e macro-regiao da residencia. O teste qui-quadrado avaliou a associacao entre variaveis categoricas. Os testes Kruskal-Wallis e Mann-Whitney foram usados para determinar diferencas do numero medio de pares de dentes posteriores em oclusao, macro-regiao e sexo. RESULTADOS: Os idosos tinham, em media, 5,49 dentes (DP = 7,93) (mediana = 0). A porcentagem de individuos totalmente edentulos foi de 54,7%. O edentulismo foi de 18,2% no arco superior e 1,9% no inferior. A meta da Organizacao Mundial da Saude foi alcancada por 10% dos individuos; no entanto, 2,7% tinham a funcao mastigatoria e estetica aceitaveis (com pelo menos o arco dental reduzido). Entre esses, o numero medio de pares de oclusao posterior foi 6,94 (DP = 2,97). A presenca de arco dental reduzido foi mais frequente entre homens, assim como o alcance da meta da Organizacao Mundial da Saude. Tambem se observaram diferencas quanto ao arco dental reduzido entre as macro-regioes. CONCLUSOES: O levantamento epidemiologico de saude bucal brasileira apresentou alto percentual de edentulismo e baixo de arco dental reduzido, sugerindo o comprometimento funcional e estetico consideravel em todas as regioes do Pais, especialmente entre mulheres.

Validity and reproducibility of the revised oral assessment guide applied by community health workers

OBJECTIVE To determine the validity and reproducibility of the Revised Oral Assessment Guide (ROAG) as pre-diagnostic tool used in elderly citizens by community health workers (CHWs) of the Family Health Strategy (FHS). MATERIAL AND METHODS Initially, we adjusted the English version to Portuguese and then developed a training program for use of ROAG, with the participation of CHWs, in selected districts that had the highest enrolled number of elderly people in the city. The elderly persons were distributed among 10 previously trained CHWs. To assess the validity of the ROAG, a CHW and a dentist (considered as the gold standard) independently evaluated the same individual. The reproducibility of the ROAG was evaluated by each of the CHWs examining 5-6 elderly individuals twice with a 7-day interval. RESULTS The sensitivity ranged from 0.17 for evaluation of saliva to 0.80 for voice. The specific ranged from 0.69 for teeth/dentures to 0.98 for saliva using mirror and the accuracy ranged from 0.92 for swallow to 0.64 for mucosa. The intra-rater reproducibility of the ROAG was perfect for evaluation of voice, lips and swallow (κ=1.000). CONCLUSION When used by trained CHWs, the ROAG is a tool with high sensitivity and specificity to assess voice, swallowing, tongue and teeth/dentures. Moreover, it can efficiently detect patients showing no alteration in lips, saliva, mucosa and gums. High reproducibility was observed in almost all the categories. Trained CHWs can use this tool to improve the access of elderly patients to dental services.

Adaptação transcultural e reprodutibilidade de questionário para avaliação de conhecimento e atitude de profissionais de saúde frente a casos de abuso físico infantil

The scope of this study was to conduct cross-cultural adaptation and evaluate the reproducibility of a questionnaire designed by a team from the University of London to assess knowledge and attitudes of health professionals during primary care when faced with cases of child physical abuse. The translation rigorously followed the criteria described by Herdman (1998), to maintain maximum functional equivalence. The adapted questionnaire was tested on 107 health care professionals from Belo Horizonte. Standard and Weighted Kappa tests were used to evaluate the reproducibility of the instrument. Most of the questions achieved Kappa test values above 80% (excellent). The Brazilian version of the questionnaire was, therefore, adapted and had proven reproducibility.

Miíase bucal e doença de Alzheimer: relato de caso clínico

Miiase e uma afeccao causada pela presenca de larvas de moscas em orgaos e/ou tecidos do homem ou de outros animais vertebrados, sendo mais frequentemente observada em paises tropicais. A ocorrencia de miiase na cavidade bucal e rara. Dentre os fatores predisponentes, destacam-se a senilidade, o comprometimento neurologico e a halitose. Assim, pacientes com doencas neuro-degenerativas, como a doenca de Alzheimer (DA), sao mais propensos a adquirirem essa alteracao. Este trabalho relata um caso de miiase bucal, acometendo um paciente de 67 anos de idade, com DA em fase avancada, totalmente dependente para as atividades de vida diaria (AVD), residente em uma instituicao de longa permanencia (ILP). O paciente apresentava falta de selamento labial e resistencia aos cuidados de higiene bucal. O diagnostico foi estabelecido clinicamente com base na observacao de sangramento na regiao anterior do palato, descolamento da mucosa bucal e presenca de larvas. Foi prescrito o uso de ivermectina e o paciente foi hospitalizado para debridamento do tecido necrotico e remocao das larvas. Apos a alta, os cuidadores foram orientados quanto ao uso de mascara pelo paciente, que nao se mostrou efetiva, pois o paciente passou a morde-la, levando a seu deslocamento e reinfestacao por larvas. Apos o tratamento da reinfestacao, adotou-se o uso de cortinado como rotina. Pacientes com DA constituem um grupo de risco para miiase bucal, sendo necessario orientar cuidadores e familiares em relacao aos cuidados odontologicos para a prevencao desta patologia. O principal tratamento para a alteracao baseia-se na remocao mecânica das larvas e instituicao do uso oral da ivermectina.

Association between the degree of physical impairment from leprosy and dependence in activities of daily living among the elderly in a health unit in the State of Minas Gerais

INTRODUCTION In addition to the common alterations and diseases inherent in the aging process, elderly persons with a history of leprosy are particularly vulnerable to dependence because of disease-related impairments. OBJECTIVE determine whether physical impairment from leprosy is associated with dependence among the elderly. METHODS An analytical cross-sectional study of elderly individuals with a history of leprosy and no signs of cognitive impairment was conducted using a database from a former leprosy colony-hospital. The patients were evaluated for dependence in the basic activities of daily living (BADL) and instrumental activities of daily living (IADL), respectively) and subjected to standard leprosy physical disability grading. Subsequently, descriptive and univariate analyses were conducted, the latter using Pearsons chi-squared test. RESULTS A total of 186 elderly persons were included in the study. Of these individuals, 53.8% were women, 49.5% were older than 75 years of age, 93% had four or less years of formal education, 24.2% lived in an institution for the long-term care of the elderly (ILTC), and 18.3% had lower limb amputations. Among those evaluated, 79.8% had visible physical impairments from leprosy (grade 2), 83.3% were independent in BADL, and 10.2% were independent in IADL. There was a higher impairment grade among those patients who were IADL dependent (p=0.038). CONCLUSIONS The leprosy physical impairment grade is associated with dependence for IADL, creating the need for greater social support and systematic monitoring by a multidisciplinary team. The results highlight the importance of early diagnosis and treatment of leprosy to prevent physical impairment and dependence in later years.

Cuidados odontológicos na paralisia supranuclear progressiva: relato de caso

This study aimed to report the treatment of oral complications in hospitalized patients diagnosed with progressive supranuclear palsy (PSP), the most common cause of degenerative parkinsonism. The patient was taking several medications, was 70 years old, without dental monitoring during hospitalization, with partial edentulism (without natural teeth in upper arch) and used a lower partial denture, but due to clinical history she was not using it. On examination, there was an oral mucosal damage and upper lip due to trauma of the lower teeth. It was planned to initially treat the lesion with laser therapy and extractions of teeth that caused the traumatic injury. After healing of the injury, the remaining lower teeth were extracted. The results of the treatment applied were effective in improving the clinical condition of the patient. This case report showed the need for a dentist as permanent member of the multidisciplinary team to treat this type and other conditions to allow better quality of life for patients.