This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
There has been growing interest on forecasting mortality. In this article, we propose a novel dyn... more There has been growing interest on forecasting mortality. In this article, we propose a novel dynamic Bayesian approach for modeling and forecasting the age-at-death distribution, focusing on a three-components mixture of a Dirac mass, a Gaussian distribution and a Skew-Normal distribution. According to the specified model, the age-at-death distribution is characterized via seven parameters corresponding to the main aspects of infant, adult and old-age mortality. The proposed approach focuses on coherent modeling of multiple countries, and following a Bayesian approach to inference we allow to borrow information across populations and to shrink parameters towards a common mean level, implicitly penalizing diverging scenarios. Dynamic modeling across years is induced trough an hierarchical dynamic prior distribution that allows to characterize the temporal evolution of each mortality component and to forecast the age-at-death distribution. Empirical results on multiple countries indi...
Fertility rates show dynamically–varying shapes when modeled as a function of the age at delivery... more Fertility rates show dynamically–varying shapes when modeled as a function of the age at delivery. We incorporate this behavior under a novel Bayesian approach for dynamic modeling of proportionate age–specific fertility rates via skewed processes. The model assumes a skew–normal distribution for the age at the moment of childbirth, while allowing the location and the skewness parameters to evolve in time via Gaussian processes priors. Posterior inference is performed via Monte Carlo methods, leveraging results on unified skew–normal distributions. The proposed approach is illustrated on Italian age–specific fertility rates from 1991 to 2014, providing forecasts until 2030.
Stats under the Stars is an event aimed at fostering the dynamic link be- tween Statistics and yo... more Stats under the Stars is an event aimed at fostering the dynamic link be- tween Statistics and young people. An all night-long challenge among teams of young data scientists taking place between the 8th and 9th of September 2015. A clash that represented not only an opportunity to meet and exchange ideas, but also a way to highlight the usefulness of Statistics as a key decision making tool.
Taste dysfunction (TD) has been recognised, together with olfactory dysfunction, as a key present... more Taste dysfunction (TD) has been recognised, together with olfactory dysfunction, as a key presenting symptom of COVID-19. The capability to recognise flavours, flavour intensities and aroma characteristics can be highly variable within the same population, as well as potentially diverse between culturally different populations. The aims of this study are to evaluate whether a difference in the types of TD presentation amongst COVID-19 positive subjects can be demonstrated and whether a difference exists between populations of different cultures.
The etiology of age-related olfactory loss is still unclear, but it has been claimed that polypha... more The etiology of age-related olfactory loss is still unclear, but it has been claimed that polypharmacotherapy may contribute to olfactory dysfunction, particularly in the elderly, who are more likely to need multiple drugs. The present pilot study investigated the relationship between smell and the number and type of drugs taken in a group of elderly. Methodology: 50 elderly volunteers (≥65 years old) who were healthy from the sinonasal standpoint (SNOT 22<1) and had no cognitive impairments [Mini Mental State Examination (MMSE) > 18] were administered the Screening 12 test® and tested on their n-butanol olfactory threshold. Their olfactory performance was then connected with the number and type of drugs participants used. The mean age of the included volunteers was 74±7 years. No association emerged between odor identification and number of drugs taken. The number of drugs taken correlated directly with a worse olfactory threshold and with a worse MMSE score, meaning a worse cognitive status. Odor identification significantly worsened with age. Comparing those volunteers taking only one drug known to not influence olfaction with another sub-group of volunteers taking five or more drugs, it was evident that subjects taking only one drug scored significantly better in olfactory threshold test and MMSE, and marginally better in olfactory identification test. For what concerns the difference between male and female volunteers, no difference in olfactory test result was shown, both for threshold and identification. Univariate analysis showed a direct correlation between the consumption of calcium channel blockers, ß-blockers, acetylsalicylic acid and olfactory threshold, meaning a worse sense of smell. Acetylsalicylic acid also correlated inversely with odor identification, meaning again a worse sense of smell, and so did potassium-sparing diuretics. Multivariate analysis showed that MMSE scores correlated with a better sense of smell, that is a lower olfactory threshold, and that α-blockers and acetylsalicylic acid negatively affected olfactory threshold, meaning a worse sense of smell. Acetylsalicylic acid also correlated inversely with odor identification, meaning again a worse sense of smell. The number of drugs taken demonstrated to be significantly correlated with a worse olfactory threshold and worse MMSE. Larger studies on elderly volunteers are needed to confirm these preliminary findings.
With the collaboration of Italian centres providing services on natural family planning, a prospe... more With the collaboration of Italian centres providing services on natural family planning, a prospective study collected data on 2755 menstrual cycles of 193 women. A database was constructed using information on the daily characteristics of cervical mucus and episodes of intercourse. Taking the day of peak mucus as a conventional marker of ovulation, the database identified the length (12 days) and location of a ‘window’ of potential fertility, the highest level of conception probability being confined to the central five to six days. Univariate analysis provided evidence of the impact on fecundability of the woman’s age and the basic infertile pattern of a cycle. Several analytical approaches highlighted the relationship between daily mucus characteristics and levels of fecundability.
Riassunto: La segmentazione della Customer Base e in particolare il profiling dei com-portamenti ... more Riassunto: La segmentazione della Customer Base e in particolare il profiling dei com-portamenti dei signoli clienti rispetto all'utilizzo e fruizione dei prodotti e servizi ca-ratterizza, ormai, la strategia di marketing di molte aziende. In particolare, le aziende che richiedono una continua ...
Journal of the American Statistical Association, 2014
In many applications involving functional data, prior information is available about the proporti... more In many applications involving functional data, prior information is available about the proportion of curves having different attributes. It is not straightforward to include such information in existing procedures for functional data analysis. Generalizing the functional Dirichlet process (FDP), we propose a class of stick-breaking priors for distributions of functions. These priors incorporate functional atoms drawn from constrained stochastic processes. The stick-breaking weights are specified to allow user-specified prior probabilities for curve attributes, with hyperpriors accommodating uncertainty. Compared with the FDP, the random distribution is enriched for curves having attributes known to be common. Theoretical properties are considered, methods are developed for posterior computation, and the approach is illustrated using data on temperature curves in menstrual cycles.
Multivariate categorical data are common in many fields. We are motivated by election polls studi... more Multivariate categorical data are common in many fields. We are motivated by election polls studies assessing evidence of changes in voters opinions with their candidates preferences in the 2016 United States Presidential primaries or caucuses. Similar goals arise routinely in several applications, but current literature lacks a general methodology which combines flexibility, efficiency, and tractability in testing for group differences in multivariate categorical data at different-potentially complex-scales. We address this goal by leveraging a Bayesian representation which factorizes the joint probability mass function for the group variable and the multivariate categorical data as the product of the marginal probabilities for the groups, and the conditional probability mass function of the multivariate categorical data, given the group membership. To enhance flexibility, we define the conditional probability mass function of the multivariate categorical data via a group-dependent mixture of tensor factorizations, thus facilitating dimensionality reduction and borrowing of information, while providing tractable procedures for computation, and accurate tests assessing global and local group differences. We compare our methods with popular competitors, and discuss improved performance in simulations and in American election polls studies.
In modeling multivariate time series, it is important to allow time-varying smoothness in the mea... more In modeling multivariate time series, it is important to allow time-varying smoothness in the mean and covariance process. In particular, there may be certain time intervals exhibiting rapid changes and others in which changes are slow. If such time-varying smoothness is not accounted for, one can obtain misleading inferences and predictions, with oversmoothing across erratic time intervals and under-smoothing across times exhibiting slow variation. This can lead to mis-calibration of predictive intervals, which can be substantially too narrow or wide depending on the time. We propose a locally adaptive factor process for characterizing multivariate mean-covariance changes in continuous time, allowing locally varying smoothness in both the mean and covariance matrix. This process is constructed utilizing latent dictionary functions evolving in time through nested Gaussian processes and linearly related to the observed data with a sparse mapping. Using a differential equation represe...
It is well known that the sex ratio at birth is a biological constant, being about 106 boys to 10... more It is well known that the sex ratio at birth is a biological constant, being about 106 boys to 100 girls. However couples have always wanted to know and decide in advance the sex of a newborn. For example, a large number of papers appeared connecting biometrical variables, such as length of follicular phase in the woman menstrual cycle or timing of intercourse acts to the sex of new baby. In this paper, we propose a Bayesian model to validate some of these theories by using an independent database. Results show that we could not show an effect of the follicular length on the sex of the baby. We also obtain a slightly larger probability, although not significant, of conceiving a female just after the mucus peak day.
International Journal of Environmental Research and Public Health
A group of 142 bakers was studied in order to investigate the relationship between higher/lower r... more A group of 142 bakers was studied in order to investigate the relationship between higher/lower respiratory signs/symptoms and inflammation biomarkers and occupational exposure to flour dust. A complete upper and lower respiratory tract evaluation was performed. Seven percent of bakers complained of lower respiratory symptoms, while 22% of them complained of upper respiratory symptoms. Fifty five percent of the bakers were allergic, and 37.1% showed sensitization to occupational allergens. Abnormal spirometries were found in 15% of bakers, while fractional exhaled nitric oxide (FeNO) was above the normal reference in 24.5% of them. Moreover, 23.8% of bakers were found to be hyposmic. Population mean peak nasal inspiratory flow (PNIF) was in the normal range even if almost all the workers suffered from neutrophilic rhinitis at nasal cytology with the number of nasal neutrophils increasing with the increase of the duration of exposure to flour dust (p = 0.03). PNIF and FEV1 (forced ex...
ABSTRACT In this paper, we study the problem of heterogeneity in cervical mucus hydration at diff... more ABSTRACT In this paper, we study the problem of heterogeneity in cervical mucus hydration at different times relative to the mucus peak both between cycles and women, specifying and estimating appropriate multilevel latent class models for longitudinal data. We estimate multilevel and growth latent class models which classify women on the basis of the evolution of cervical mucus characteristics observed over the fertile period of each menstrual cycle taking into account that we observe a different number of cycles per woman and correlation over time between consecutive observations. The effect of potential covariates on mucus evolution patterns is as well evaluated. Results confirm the existence of heterogeneity in mucus evolution between cycles and women. Moreover, an important significant effect of a woman’s age is found.
Abnormal cortical oscillations are markers of Parkinson’s Disease (PD). Transcranial alternating ... more Abnormal cortical oscillations are markers of Parkinson’s Disease (PD). Transcranial alternating current stimulation (tACS) can modulate brain oscillations and possibly impact on behaviour. Mapping of cortical activity (prevalent oscillatory frequency and topographic scalp distribution) may provide a personalized neurotherapeutic target and guide non-invasive brain stimulation. This is a cross-over, double blinded, randomized trial. Electroencephalogram (EEG) from participants with PD were recorded. TACS frequency/site were individually defined based on statistical comparison of EEG power spectra maps with normative data from our laboratory. Participants were randomized to tACS or random noise stimulation (RNS), 5 days/week for 2-weeks followed by ad hoc physical therapy. EEG, motor (Unified Parkinson’s Disease Rating Scale-motor: UPDRS III), neuropsychological (frontal, executive and memory tests) performance and mood were measured before (T0), after (T1) and 4-weeks after treatment (T2). A linear model with random effects and Wilcoxon test were used to detect differences. Main results include a reduction of beta rhythm in theta-tACS vs. RNS group at T1 over right sensorimotor area (p = 0.014) and left parietal area (p = 0.010) and at T2 over right sensorimotor area (p = 0.004) and left frontal area (p = 0.039). Bradykinesia items improved at T1 (p = 0.002) and T2 (p = 0.047) compared to T0 in the tACS group. In the tACS group the Montreal Cognitive Assessment (MoCA) improved at T2 compared with T1 (p = 0.049). Individualized tACS in PD improves motor and cognitive performance. These changes are associated with a reduction of excessive fast oscillations.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
There has been growing interest on forecasting mortality. In this article, we propose a novel dyn... more There has been growing interest on forecasting mortality. In this article, we propose a novel dynamic Bayesian approach for modeling and forecasting the age-at-death distribution, focusing on a three-components mixture of a Dirac mass, a Gaussian distribution and a Skew-Normal distribution. According to the specified model, the age-at-death distribution is characterized via seven parameters corresponding to the main aspects of infant, adult and old-age mortality. The proposed approach focuses on coherent modeling of multiple countries, and following a Bayesian approach to inference we allow to borrow information across populations and to shrink parameters towards a common mean level, implicitly penalizing diverging scenarios. Dynamic modeling across years is induced trough an hierarchical dynamic prior distribution that allows to characterize the temporal evolution of each mortality component and to forecast the age-at-death distribution. Empirical results on multiple countries indi...
Fertility rates show dynamically–varying shapes when modeled as a function of the age at delivery... more Fertility rates show dynamically–varying shapes when modeled as a function of the age at delivery. We incorporate this behavior under a novel Bayesian approach for dynamic modeling of proportionate age–specific fertility rates via skewed processes. The model assumes a skew–normal distribution for the age at the moment of childbirth, while allowing the location and the skewness parameters to evolve in time via Gaussian processes priors. Posterior inference is performed via Monte Carlo methods, leveraging results on unified skew–normal distributions. The proposed approach is illustrated on Italian age–specific fertility rates from 1991 to 2014, providing forecasts until 2030.
Stats under the Stars is an event aimed at fostering the dynamic link be- tween Statistics and yo... more Stats under the Stars is an event aimed at fostering the dynamic link be- tween Statistics and young people. An all night-long challenge among teams of young data scientists taking place between the 8th and 9th of September 2015. A clash that represented not only an opportunity to meet and exchange ideas, but also a way to highlight the usefulness of Statistics as a key decision making tool.
Taste dysfunction (TD) has been recognised, together with olfactory dysfunction, as a key present... more Taste dysfunction (TD) has been recognised, together with olfactory dysfunction, as a key presenting symptom of COVID-19. The capability to recognise flavours, flavour intensities and aroma characteristics can be highly variable within the same population, as well as potentially diverse between culturally different populations. The aims of this study are to evaluate whether a difference in the types of TD presentation amongst COVID-19 positive subjects can be demonstrated and whether a difference exists between populations of different cultures.
The etiology of age-related olfactory loss is still unclear, but it has been claimed that polypha... more The etiology of age-related olfactory loss is still unclear, but it has been claimed that polypharmacotherapy may contribute to olfactory dysfunction, particularly in the elderly, who are more likely to need multiple drugs. The present pilot study investigated the relationship between smell and the number and type of drugs taken in a group of elderly. Methodology: 50 elderly volunteers (≥65 years old) who were healthy from the sinonasal standpoint (SNOT 22<1) and had no cognitive impairments [Mini Mental State Examination (MMSE) > 18] were administered the Screening 12 test® and tested on their n-butanol olfactory threshold. Their olfactory performance was then connected with the number and type of drugs participants used. The mean age of the included volunteers was 74±7 years. No association emerged between odor identification and number of drugs taken. The number of drugs taken correlated directly with a worse olfactory threshold and with a worse MMSE score, meaning a worse cognitive status. Odor identification significantly worsened with age. Comparing those volunteers taking only one drug known to not influence olfaction with another sub-group of volunteers taking five or more drugs, it was evident that subjects taking only one drug scored significantly better in olfactory threshold test and MMSE, and marginally better in olfactory identification test. For what concerns the difference between male and female volunteers, no difference in olfactory test result was shown, both for threshold and identification. Univariate analysis showed a direct correlation between the consumption of calcium channel blockers, ß-blockers, acetylsalicylic acid and olfactory threshold, meaning a worse sense of smell. Acetylsalicylic acid also correlated inversely with odor identification, meaning again a worse sense of smell, and so did potassium-sparing diuretics. Multivariate analysis showed that MMSE scores correlated with a better sense of smell, that is a lower olfactory threshold, and that α-blockers and acetylsalicylic acid negatively affected olfactory threshold, meaning a worse sense of smell. Acetylsalicylic acid also correlated inversely with odor identification, meaning again a worse sense of smell. The number of drugs taken demonstrated to be significantly correlated with a worse olfactory threshold and worse MMSE. Larger studies on elderly volunteers are needed to confirm these preliminary findings.
With the collaboration of Italian centres providing services on natural family planning, a prospe... more With the collaboration of Italian centres providing services on natural family planning, a prospective study collected data on 2755 menstrual cycles of 193 women. A database was constructed using information on the daily characteristics of cervical mucus and episodes of intercourse. Taking the day of peak mucus as a conventional marker of ovulation, the database identified the length (12 days) and location of a ‘window’ of potential fertility, the highest level of conception probability being confined to the central five to six days. Univariate analysis provided evidence of the impact on fecundability of the woman’s age and the basic infertile pattern of a cycle. Several analytical approaches highlighted the relationship between daily mucus characteristics and levels of fecundability.
Riassunto: La segmentazione della Customer Base e in particolare il profiling dei com-portamenti ... more Riassunto: La segmentazione della Customer Base e in particolare il profiling dei com-portamenti dei signoli clienti rispetto all'utilizzo e fruizione dei prodotti e servizi ca-ratterizza, ormai, la strategia di marketing di molte aziende. In particolare, le aziende che richiedono una continua ...
Journal of the American Statistical Association, 2014
In many applications involving functional data, prior information is available about the proporti... more In many applications involving functional data, prior information is available about the proportion of curves having different attributes. It is not straightforward to include such information in existing procedures for functional data analysis. Generalizing the functional Dirichlet process (FDP), we propose a class of stick-breaking priors for distributions of functions. These priors incorporate functional atoms drawn from constrained stochastic processes. The stick-breaking weights are specified to allow user-specified prior probabilities for curve attributes, with hyperpriors accommodating uncertainty. Compared with the FDP, the random distribution is enriched for curves having attributes known to be common. Theoretical properties are considered, methods are developed for posterior computation, and the approach is illustrated using data on temperature curves in menstrual cycles.
Multivariate categorical data are common in many fields. We are motivated by election polls studi... more Multivariate categorical data are common in many fields. We are motivated by election polls studies assessing evidence of changes in voters opinions with their candidates preferences in the 2016 United States Presidential primaries or caucuses. Similar goals arise routinely in several applications, but current literature lacks a general methodology which combines flexibility, efficiency, and tractability in testing for group differences in multivariate categorical data at different-potentially complex-scales. We address this goal by leveraging a Bayesian representation which factorizes the joint probability mass function for the group variable and the multivariate categorical data as the product of the marginal probabilities for the groups, and the conditional probability mass function of the multivariate categorical data, given the group membership. To enhance flexibility, we define the conditional probability mass function of the multivariate categorical data via a group-dependent mixture of tensor factorizations, thus facilitating dimensionality reduction and borrowing of information, while providing tractable procedures for computation, and accurate tests assessing global and local group differences. We compare our methods with popular competitors, and discuss improved performance in simulations and in American election polls studies.
In modeling multivariate time series, it is important to allow time-varying smoothness in the mea... more In modeling multivariate time series, it is important to allow time-varying smoothness in the mean and covariance process. In particular, there may be certain time intervals exhibiting rapid changes and others in which changes are slow. If such time-varying smoothness is not accounted for, one can obtain misleading inferences and predictions, with oversmoothing across erratic time intervals and under-smoothing across times exhibiting slow variation. This can lead to mis-calibration of predictive intervals, which can be substantially too narrow or wide depending on the time. We propose a locally adaptive factor process for characterizing multivariate mean-covariance changes in continuous time, allowing locally varying smoothness in both the mean and covariance matrix. This process is constructed utilizing latent dictionary functions evolving in time through nested Gaussian processes and linearly related to the observed data with a sparse mapping. Using a differential equation represe...
It is well known that the sex ratio at birth is a biological constant, being about 106 boys to 10... more It is well known that the sex ratio at birth is a biological constant, being about 106 boys to 100 girls. However couples have always wanted to know and decide in advance the sex of a newborn. For example, a large number of papers appeared connecting biometrical variables, such as length of follicular phase in the woman menstrual cycle or timing of intercourse acts to the sex of new baby. In this paper, we propose a Bayesian model to validate some of these theories by using an independent database. Results show that we could not show an effect of the follicular length on the sex of the baby. We also obtain a slightly larger probability, although not significant, of conceiving a female just after the mucus peak day.
International Journal of Environmental Research and Public Health
A group of 142 bakers was studied in order to investigate the relationship between higher/lower r... more A group of 142 bakers was studied in order to investigate the relationship between higher/lower respiratory signs/symptoms and inflammation biomarkers and occupational exposure to flour dust. A complete upper and lower respiratory tract evaluation was performed. Seven percent of bakers complained of lower respiratory symptoms, while 22% of them complained of upper respiratory symptoms. Fifty five percent of the bakers were allergic, and 37.1% showed sensitization to occupational allergens. Abnormal spirometries were found in 15% of bakers, while fractional exhaled nitric oxide (FeNO) was above the normal reference in 24.5% of them. Moreover, 23.8% of bakers were found to be hyposmic. Population mean peak nasal inspiratory flow (PNIF) was in the normal range even if almost all the workers suffered from neutrophilic rhinitis at nasal cytology with the number of nasal neutrophils increasing with the increase of the duration of exposure to flour dust (p = 0.03). PNIF and FEV1 (forced ex...
ABSTRACT In this paper, we study the problem of heterogeneity in cervical mucus hydration at diff... more ABSTRACT In this paper, we study the problem of heterogeneity in cervical mucus hydration at different times relative to the mucus peak both between cycles and women, specifying and estimating appropriate multilevel latent class models for longitudinal data. We estimate multilevel and growth latent class models which classify women on the basis of the evolution of cervical mucus characteristics observed over the fertile period of each menstrual cycle taking into account that we observe a different number of cycles per woman and correlation over time between consecutive observations. The effect of potential covariates on mucus evolution patterns is as well evaluated. Results confirm the existence of heterogeneity in mucus evolution between cycles and women. Moreover, an important significant effect of a woman’s age is found.
Abnormal cortical oscillations are markers of Parkinson’s Disease (PD). Transcranial alternating ... more Abnormal cortical oscillations are markers of Parkinson’s Disease (PD). Transcranial alternating current stimulation (tACS) can modulate brain oscillations and possibly impact on behaviour. Mapping of cortical activity (prevalent oscillatory frequency and topographic scalp distribution) may provide a personalized neurotherapeutic target and guide non-invasive brain stimulation. This is a cross-over, double blinded, randomized trial. Electroencephalogram (EEG) from participants with PD were recorded. TACS frequency/site were individually defined based on statistical comparison of EEG power spectra maps with normative data from our laboratory. Participants were randomized to tACS or random noise stimulation (RNS), 5 days/week for 2-weeks followed by ad hoc physical therapy. EEG, motor (Unified Parkinson’s Disease Rating Scale-motor: UPDRS III), neuropsychological (frontal, executive and memory tests) performance and mood were measured before (T0), after (T1) and 4-weeks after treatment (T2). A linear model with random effects and Wilcoxon test were used to detect differences. Main results include a reduction of beta rhythm in theta-tACS vs. RNS group at T1 over right sensorimotor area (p = 0.014) and left parietal area (p = 0.010) and at T2 over right sensorimotor area (p = 0.004) and left frontal area (p = 0.039). Bradykinesia items improved at T1 (p = 0.002) and T2 (p = 0.047) compared to T0 in the tACS group. In the tACS group the Montreal Cognitive Assessment (MoCA) improved at T2 compared with T1 (p = 0.049). Individualized tACS in PD improves motor and cognitive performance. These changes are associated with a reduction of excessive fast oscillations.
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