A two sample size estimator for large data sets

In GMM estimators moment conditions with additive error terms involve an observed component and a predicted component. If the predicted component is computationally costly to evaluate, it may not be feasible to estimate the model with all the available data. We propose an estimator that uses the full data set for the computationally cheap observed component, but a reduced sample size for the predicted component. We show consistency, asymptotic normality, and derive standard errors and a practical criterion for when our estimator is variance-reducing. We demonstrate the estimator’s properties on a range of models through Monte Carlo studies and an empirical application to alcohol demand

Logical Predictivism

Motivated by weaknesses with traditional accounts of logical epistemology, considerable attention has been paid recently to the view, known as anti-exceptionalism about logic (AEL), that the subject matter and epistemology of logic may not be so different from that of the recognised sciences. One of the most prevalent claims made by advocates of AEL is that theory choice within logic is significantly similar to that within the sciences. This connection with scientific methodology highlights a considerable challenge for the anti-exceptionalist, as two uncontentious claims about scientific theories are that they attempt to explain a target phenomenon and (at least partially) prove their worth through successful predictions. Thus, if this methodological AEL is to be viable, the anti-exceptionalist will need a reasonable account of what phenomena logics are attempting to explain, how they can explain, and in what sense they can be said to issue predictions. This paper makes sense of the anti-exceptionalist proposal with a new account of logical theory choice, logical predictivism, according to which logics are engaged in both a process of prediction and explanation.publishedVersio

Social isolation affects intra-specific interaction behaviour and reduces the size of the cerebellar brain region in juvenile Atlantic salmon Salmo salar

The social environment can affect the development of behavioural phenotypes in fish, and it is important to understand such effects when rearing fish in artificial environments. Here, the authors test the effects of spatial isolation on social interaction propensity and brain development in hatchery-reared Atlantic salmon Salmo salar L. Salmon reared in isolation generally stayed further away from a conspecific in a standardized intruder test than conspecifics reared together in groups. Isolated salmon also tended to be more active in an intruder test, albeit non-significantly so, but this pattern was not detected in open-field tests without an intruding conspecific. The cerebellar brain region was relatively smaller in isolated salmon, suggesting that the brain was developing differently in these fish. Therefore, some features of the behavioural and neural phenotype are affected by rearing in isolation. These effects should be considered when rearing salmon, particularly for experimental purposes as it may affect results of laboratory studies on behavioural expression and brain size

Evidence in Logic

The historical consensus is that logical evidence is special. Whereas empirical evidence is used to support theories within both the natural and social sciences, logic answers solely to a priori evidence. Further, unlike other areas of research that rely upon a priori evidence, such as mathematics, logical evidence is basic. While we can assume the validity of certain inferences in order to establish truths within mathematics and test scientific theories, logicians cannot use results from mathematics or the empirical sciences without seemingly begging the question. Appeals to rational intuition and analyticity in order to account for logical knowledge are symptomatic of these commitments to the apriority and basicness of logical evidence. This chapter argues that these historically prevalent accounts of logical evidence are mistaken, and that if we take logical practice seriously we find that logical evidence is rather unexceptional, sharing many similarities to the types of evidence appealed to within other research areas

Intensjon ved bytte av bank

Formålet med denne oppgaven og dens hovedtema er intensjon ved bytte av bank. På bakgrunn av temaet har vi derfor valgt problemstillingen “Hva påvirker intensjonslojaliteten til en bankkunde?”. Oppgaven er forankret i problemstillingen, der målet er å gi en god redegjørelse for hva som påvirker intensjonslojalitet. I teorikapittelet tar vi for oss relevant teori, basert på forskning og studier. Oppgaven er inspirert av forskning gjort av Rusbult, Martz og Agnew. De har forsket på commitment i et kjærlighetsforhold, der de har utviklet en investeringsmodell. På bakgrunn av dette anser vi det å være i et kjærlighetsforhold som svært sammenlignbart med å være i et bankforhold. Teorien tar for seg lojalitet, tilfredshet, kvalitet på alternativer og byttekostnader, der vi har utviklet tre hypoteser: H1: Tilfredshet har en negativ virkning på bytte av bank. H2: Kvalitet på alternativer har en positiv virkning på bytte av bank. H3: Opplevd byttekostnad har en negativ virkning på bytte av bank. Vi brukte en kvantitativ metode der vi sendte ut en spørreundersøkelse på Internett ved hjelp av Qualtrics. Undersøkelsen delte vi på mail, Luvit og Facebook. Vi fikk 215 respondenter i alderen 20 - 62 år. Ved hjelp av Rusbult, Martz og Agnew sin modell har vi sett på sammenhengen mellom intensjonslojalitet og tilfredshet, konkurrenters inntrykk og byttekostnader i et bankforhold. Vi har funnet ut at tilfredshet hadde en positiv sammenheng med lojalitet. Noe som ga en indikator på at jo mer tilfreds man er, jo mer lojal er man. Ved konkurrenters inntrykk fant vi at jo mer tiltrekkende kvaliteten på alternativene ser ut, jo mer sannsynlig er det å bytte. Likeledes, jo mindre kvalitet på alternativene, jo større sannsynlighet for å bli i bankforholdet. Til slutt fant vi at jo høyere kundene opplevde byttekostnadene, jo mer sannsynlig var det at de ble i bankforholdet. Vi så også at det bare var finansielle byttekostnader som hadde en sammenheng med lojalitet

Clonal expansion and linear genome evolution through breast cancer progression from pre-invasive stages to asynchronous metastasis

Evolution of the breast cancer genome from pre-invasive stages to asynchronous metastasis is complex and mostly unexplored, but highly demanded as it may provide novel markers for and mechanistic insights in cancer progression. The increasing use of personalized therapy of breast cancer necessitates knowledge of the degree of genomic concordance between different steps of malignant progression as primary tumors often are used as surrogates of systemic disease. Based on exome sequencing we performed copy number profiling and point mutation detection on successive steps of breast cancer progression from one breast cancer patient, including two different regions of Ductal Carcinoma In Situ (DCIS), primary tumor and an asynchronous metastasis. We identify a remarkable landscape of somatic mutations, retained throughout breast cancer progression and with new mutational events emerging at each step. Our data, contrary to the proposed model of early dissemination of metastatic cells and parallel progression of primary tumors and metastases, provide evidence of linear progression of breast cancer with relatively late dissemination from the primary tumor. The genomic discordance between the different stages of tumor evolution in this patient emphasizes the importance of molecular profiling of metastatic tissue directing molecularly targeted therapy at recurrence