Inferential Implications of Over-Parametrization: A Case Study in Incomplete Categorical Data

P>In the context of either Bayesian or classical sensitivity analyses of over-parametrized models for incomplete categorical data, it is well known that prior-dependence on posterior inferences of nonidentifiable parameters or that too parsimonious over-parametrized models may lead to erroneous conclusions. Nevertheless, some authors either pay no attention to which parameters are nonidentifiable or do not appropriately account for possible prior-dependence. We review the literature on this topic and consider simple examples to emphasize that in both inferential frameworks, the subjective components can influence results in nontrivial ways, irrespectively of the sample size. Specifically, we show that prior distributions commonly regarded as slightly informative or noninformative may actually be too informative for nonidentifiable parameters, and that the choice of over-parametrized models may drastically impact the results, suggesting that a careful examination of their effects should be considered before drawing conclusions.Resume Que ce soit dans un cadre Bayesien ou classique, il est bien connu que la surparametrisation, dans les modeles pour donnees categorielles incompletes, peut conduire a des conclusions erronees. Cependant, certains auteurs persistent a negliger les problemes lies a la presence de parametres non identifies. Nous passons en revue la litterature dans ce domaine, et considerons quelques exemples surparametres simples dans lesquels les elements subjectifs influencent de facon non negligeable les resultats, independamment de la taille des echantillons. Plus precisement, nous montrons comment des a priori consideres comme peu ou non-informatifs peuvent se reveler extremement informatifs en ce qui concerne les parametres non identifies, et que le recours a des modeles surparametres peut avoir sur les conclusions finales un impact considerable. Ceci suggere un examen tres attentif de l`impact potentiel des a priori.

On the motion under focal attraction in a rotating medium

New results are established here on the phase portraits and bifurcations of the kinematic model in system (1), first presented by H.K. Wilson in [3], and by him attributed to L. Markus (unpublished). A new, self-sufficient, study which extends that of [3] and allows an essential conclusion for the applicability of the model is reported here.

Piano Performance at the New York Trade School

A piano player is shown performing at the New York Trade School. He is likely playing on a piano tuned or built by students in the Piano Crafts Department at the school. Black and white photograph.

Electrical Lecture

Students fill a lecture room at the New York Trade School. The illustration on the board indicates that this is probably a lecture in the Electrical Department. Black and white photograph.

Ett rikare språk med bildmunta : Vad är ett rikt språk och kan bildskapande stimulera till ett rikare språk

A richer language when painting before speaking? – What is a rich language and can painting stimulate towards a richer language?In this work I seek to answer two questions. What may a “richer” language mean and does it become richer when the informants, as a preparation, paint what they are going to talk about in front of the class, than when they do not paint? This I try to do by studying earlyer research about how to measure the richness in languages and by analysing video recordings of speeches when the students in an sfi-class (Swedish for foreigners) painted or did not paint before the speech, and by analysing the richness in their language. The result is my own definition of what rich language is in this context, and a conclusion that painting stimulates the students to use more words and to use specific words that they need to bring the audience their message.

Metamorphic epiphany -- 3D animation

As far back as I can remember, I have always been interested in studio art. Whether it be painting, drawing, printmaking, or photography, it has consistently been a part of my life. Upon enrolling in Colby, I became interested in computers and decided to major my undergraduate college career in Computer Science. Not forgetting past interests, I continued my studio art education, taking several classes within the Art department. In due time, I began combining interests and began studying Computer Graphics and Design. With limited resources in this field at Colby, the majority of my computer graphic education and experience has been done on my own time apart from regular classroom work. As time progressed, so did my interests. Starting with simple image manipulation of digitally scanned photographs, I moved on to Web Page design, eventually leading to Desktop Publishing. Ultimately, I wanted to take a step further and expand my overall computer graphic knowledge by learning 3D modeling and animation. With even fewer resources in 3D animation at Colby, I perceived having trouble finding the information and tools I would need to gain the necessary skills for this new field. The Senior Scholars program gave me the opponunity to find and acquire the necessary tools to pursue my interest. This program also allowed me to devote the proper amount of time required for learning these new tools.