Breast Cancer Subtypes Can Be Determinant in The Decision Making Process to Avoid Surgical Axillary Staging: A retrospective cohort study

Purpose: The need for performing axillary lymph-node dissection in early breast cancer when the sentinel lymph node (SLN) is positive has been questioned in recent years. The purpose of this study was to identify a lowrisk subgroup of early breast cancer patients in whom surgical axillary staging could be avoided, and to assess the probability of having a positive lymph-node (LN). Methods: We retrospectively evaluated 612 consecutive women affected by early breast cancer. We considered age, tumour size, histological grade, vascular invasion, lymphatic invasion and cancer subtype (Luminal A, Luminal B HER-2+, Luminal B HER-2-, HER-2+, and Triple Negative) as variables for univariate and multivariate analyses to assess probability of there being a positive SLN o non-sentinel lymph node (NSLN). Chi-square, Fisher’s Exact test and Student’s t tests were used to investigate the relationship between variables; whereas logit models were used to estimate and quantify the strength of the relationship among some covariates and SLN or the number of metastases. Results: A significant positive effect of vascular invasion and lymphatic invasion, and a negative effect of TN were noted. With respect to positive NSLN, size alone has a significant (positive) effect on tumour presence, but focusing on the number of metastases, also age has a (negative) significant effect. Conclusion: This work shows correlation between subtypes and the probability of having positive SLN. Patients not expressing vascular invasion, lymphatic invasion and, moreover, a triple-negative tumor subtype may be good candidates for breast conservative surgery without axillary su

Italian University student evaluation of teaching: does it change over time?

This paper concerns a study on students’ perceived teacher activities quality. The aim is investigate about the changes over time of the students’ opinions. To evaluate the perceived teachers’ activities quality a Partial Credit Model is considered. This model allows to transform the ordinal data – collected through a questionnaire filled in by the students of a Faculty of University of Pavia, Italy – into interval scale data. To evaluate changes over time, the outcomes of the Rasch analysis are compared for three academic years: results show invariance – during the three years – of the assessment of the students on the aspects of the teachers’ activity and variability in the mean levels of satisfaction

Hints of latent drivers investigating university student performance

Job market, nowadays, asks for higher and higher skills and competences. Therefore, also the measurement and assessment of the university students performance are crucial issues for policy makers. Although the scientific literature provides several papers investigating the main determinants of university student performance, often results are very different, and they seem to hold just in very specific contexts. This paper aims to contribute to the international literature, focusing on the role of student specific characteristics, supporting the idea that unobservable variables (such as motivation, aptitudes or abilities) should be more investigated

Italian University student evaluation of teaching: does it changes over time?

This paper concerns the measurement of the Student Evaluation of Teaching (SET) by undergraduates. For almost 15 years Italian Universities have been monitoring that aspect, performing on students’ opinions about teaching, e.g. on teacher punctuality, clearness and willingness, and on suitability of the facility, logistics, and on course scheduling and managing. Each University carries out a survey with own procedures and through a questionnaire consisting of two set of items: a set of items equal for all Italian Universities, and a set of items built by each University. The survey basic aim is to gather information on teaching skill, educational goals, coordination among teachings, and adequacy of resources. This information is useful to policy makers to improve the SET and the Degree Courses. The main aim of this paper is to investigate changes over time of the SET. Teacher’s quality is obviously a concept that cannot be directly measurable. It is a latent concept and its measurement needs the specification of convenient measurable dimensions that are strictly correlated to the concept. The above mentioned questionnaire includes items that refer to SET. The items are measured by a Likert-type scale with 4 response categories. To analyse SET and its changes over the time, a Rasch model (Rasch, 1966) is used: it is necessary to transform the data from ordinal scale to interval one and to preserve the rank ordering (Doig and Groves, 2006). Rasch model gives items and persons measures on the same continuum: this is very useful to make comparisons among items, among students satisfaction levels, and among items and satisfaction levels, and finally among different points of time. The partial credit model for rating scales (Masters, 1988; Curtis and Bowman, 2007) appears the useful procedure for the analysis of these items. The dataset regards the questionnaires administrated and collected by the Engineering Faculty of the University of Pavia during three academic years - from 2004/05 to 2006/07. The 3-years period is taken into consideration because it is the longest period over the questionnaires structure and items have not been modified. The statistical unit is the teaching. The focus is on 5 teachings chosen among those performed by the same teacher during the considered period and with many students. Results show: 1) the satisfaction mean level is mainly medium-high, and seems varying over time, 2) the items and person measures are graphically compared to emphasize overall satisfaction vs. single item perceived quality, and more and less appreciated aspect of SET, and their variation over the time

L'imputazione dei dati mancanti: l'effetto sui parametri di un Extended Logistic Rasch Model

Il problema dei dati mancanti è abbastanza comune nella ricerca empirica, specialmente nelle scienze sociali in cui il tentativo di misurazione di quantità non direttamente osservabili (variabili latenti)avviene attraverso la somministrazione di test o questionari costituiti da più item. I modelli statistici finalizzati alla soluzione di tale problema richiedono, in genere, un elevato numero di osservazioni per ogni unità coinvolta nell’analisi. In un contesto multivariato il problema si amplifica, poiché nel modello sono considerati più item per ciascuna osservazione: la probabilità, quindi, di avere almeno un dato mancante non è irrilevante ed è, inoltre, crescente al crescere del numero di item. Dopo una breve panoramica di alcuni dei principali approcci ai dati mancanti, il lavoro pone l’attenzione sul metodo della Multiple Imputation, valutandone i vantaggi tramite il confronto con altri tre approcci noti e largamente usati in letteratura. L’esempio che viene riportato si focalizza sul confronto dell’efficienza delle stime dei parametri di posizione degli item quando si applica l’Extended Logistic Model (ELM) di Rasch. L’ambito applicativo a cui si vuole fare qui riferimento è quello della valutazione della didattica universitaria, da anni adottata da tutti gli Atenei pubblici italiani

Degree course change and student performance: a mixed-effect approach

This paper focuses on students credits earning speed over time and its determinants, dealing with the huge percentage of students who do not take the degree within the legal duration in the Italian University System. A new indicator for the performance of the student career is proposed on real data, concerning the cohort of students enrolled at a Faculty of the University of Palermo (followed for 7 years). The new indicator highlights a typical zero-inflated distribution and suggests to investigate the effect of the degree course (DC) change on the student career. A mixed-effect model for overdispersed data is considered, with the aim of taking into account the individual variability as well, due to the longitudinal nature of data. Results show the significant positive effect of the DC change on the student performance

IANUS - Metodologia pratica. Risultato N° 8. Appendice

Insieme all'applicazione del modello IANUS nelle strutture selezionate, si è sviluppata la concettualizzazione e la verifica di una metodologia per l'analisi comparativa. L'obiettivo di questo studio è mostrare i dati ottenuti, gli indicatori calcolati e i modi di effettuare confronti attraverso il sistema indicato di valutazione degli indicatori

The student talent in a random effects Quantile Regression Model for university performance

This paper is a development of a previous work on performance of Italian university students. A Quantile Regression was carried out on a proposed performance indicator, based on a transformation of the median of the marks weighted by credits. Results suggested to investigate the role of students peculiar features on their performance, measured by the transformation of the weighted marks. Therefore, a random intercept Quantile Regression model is fitted on real data concerning graduates over the legal university duration set in Italy, enrolled in 2002 in two Degree Courses of the University of Palermo. Results show that the student performance seems to be influenced by the student's aptitudes, motivation, interest or more in general the students talent, rather than socio-demographic characteristics