Two Kinds of Logical Impossibility

In this paper, we argue that a distinction ought to be drawn between two ways in which a given world might be logically impossible. First, a world w might be impossible because the laws that hold at w are different from those that hold at some other world (say the actual world). Second, a world w might be impossible because the laws of logic that hold in some world (say the actual world) are violated at w. We develop a novel way of modelling logical possibility that makes room for both kinds of logical impossibility. Doing so has interesting implications for the relationship between logical possibility and other kinds of possibility (for example, metaphysical possibility) and implications for the necessity or contingency of the laws of logic

Strictly speaking

A type of argument occasionally made in metaethics, epistemology and philosophy of science notes that most ordinary uses of some expression fail to satisfy the strictest interpretation of the expression, and concludes that the ordinary assertions are false. This requires there to be a presumption in favour of a strict interpretation of expressions that admit of interpretations at different levels of strictness. We argue that this presumption is unmotivated, and thus the arguments fail

Proxying ability by family background in returns to schooling estimations is generally a bad idea

A regression model is considered where earnings are explained by schooling and ability. It is assumed that schooling is measured with error and that there are no data on ability. Regressing earnings on observed schooling then yields an estimate of the return to schooling that is subject to positive omitted variable bias (OVB) and negative measurement error bias (MEB). The effects on the OVB and the MEB from using family background variables as proxies for ability are investigated theoretically and empirically. The theoretical analysis demonstrates that the impact on the OVB is uncertain, while the MEB invariably increases in magnitude. The empirical analysis shows that the MEB generally dominates the OVB. As the measurement error increases and/or more family background variables are added, the total bias rapidly becomes negative, driving the estimated return further and further away from the true value.Missing data; proxy variables; measurement error; consistent estimates of omitted variable bias and measurement error bias

On Frame Asynchronous Coded Slotted ALOHA: Asymptotic, Finite Length, and Delay Analysis

We consider a frame asynchronous coded slotted ALOHA (FA-CSA) system for uncoordinated multiple access, where users join the system on a slot-by-slot basis according to a Poisson random process and, in contrast to standard frame synchronous CSA (FS-CSA), users are not frame-synchronized. We analyze the performance of FA-CSA in terms of packet loss rate and delay. In particular, we derive the (approximate) density evolution that characterizes the asymptotic performance of FA-CSA when the frame length goes to infinity. We show that, if the receiver can monitor the system before anyone starts transmitting, a boundary effect similar to that of spatially-coupled codes occurs, which greatly improves the iterative decoding threshold. Furthermore, we derive tight approximations of the error floor (EF) for the finite frame length regime, based on the probability of occurrence of the most frequent stopping sets. We show that, in general, FA-CSA provides better performance in both the EF and waterfall regions as compared to FS-CSA. Moreover, FA-CSA exhibits better delay properties than FS-CSA.Comment: 13 pages, 12 figures. arXiv admin note: substantial text overlap with arXiv:1604.0629

Medic, suomalainen lääke-ja terveystieteellinen viitetietokanta

Terhi Sandgrenin esitys ARTIVA-seminaarissa Helsingissä 5.2.2014

Muscle dysmorphia research neglects DSM-5 diagnostic criteria

This systematic review aimed to collect, evaluate, and synthesize the research on muscle dysmorphia (MD) post official recognition as a specifier for body dysmorphic disorder (BDD) in the DSM-5, and provide recommendations for future research. Literature searches were conducted in four databases to see if inclusion criteria were met. Results revealed 33 studies meeting inclusion criteria, none of which utilized DSM-5 criteria for MD and/or acknowledged the criterion in their research. Few studies acknowledged the association between MD and BDD, and the methodological quality of recent MD research was considered low due to a lack of clinical samples, measurements not using validated cut-off scores, and the research designs. In conclusion, future MD research is encouraged to utilize DSM-5 diagnostic criteria to better inform clinical practice; and significantly improve the methodological quality. As such, more effective treatment options may be developed reducing the risk of health harming consequences in these individuals

The effect of early cognitive ability on earnings over the life-cycle

This paper utilizes information on cognitive ability at age ten and earnings information from age 20 to 65 to estimate the return to ability over the life-cycle. Ability measured at an early age is not influenced by the individual’s choices of schooling and other circumstances. We find that most of the unconditional return to early cognitive ability goes through educational choice. The conditional return is increasing for low levels of experience and non-increasing for experience above about 15-25 years. The return is similar for men and women, and highest for individuals with academic education. Only a small part of the return can be explained by higher probability to have a supervisory position.Cognitive ability; life-cycle; earnings; IQ

The effect of education on cognitive ability

We analyze whether the amount of schooling influences intelligence as measured by IQ tests. By use of a novel longitudinal dataset we are able to condition on early cognitive ability to account for selection into non-compulsory schooling when estimating the effect on cognitive ability at age 20. OLS estimates indicate that one year of schooling increases IQ by 2.8-3.5 points (about 0.2 standard deviations). When family income per family member and teacher evaluations of the individuals at age 10 are used as instruments for schooling and early cognitive ability, the return to schooling is estimated to 3.5-3.8 IQ points.Cognitive ability; Education production; Return to schooling

Asymptotic and Finite Frame Length Analysis of Frame Asynchronous Coded Slotted ALOHA

We consider a frame-asynchronous coded slotted ALOHA (FA-CSA) system where users become active according to a Poisson random process. In contrast to standard frame-synchronous CSA (FS-CSA), users transmit a first replica of their message in the slot following their activation and other replicas uniformly at random in a number of subsequent slots. We derive the (approximate) density evolution that characterizes the asymptotic performance of FA-CSA when the frame length goes to infinity. We show that, if users can monitor the system before they start transmitting, a boundary-effect similar to that of spatially-coupled codes occurs, which greatly improves the decoding threshold as compared to FS-CSA. We also derive analytical approximations of the error floor (EF) in the finite frame length regime. We show that FA-CSA yields in general lower EF, better performance in the waterfall region, and lower average delay, as compared to FS-CSA.Comment: 5 pages, 6 figures. Updated notation, terminology, and typo

An Empirical Approach to Temporal Reference Resolution

This paper presents the results of an empirical investigation of temporal reference resolution in scheduling dialogs. The algorithm adopted is primarily a linear-recency based approach that does not include a model of global focus. A fully automatic system has been developed and evaluated on unseen test data with good results. This paper presents the results of an intercoder reliability study, a model of temporal reference resolution that supports linear recency and has very good coverage, the results of the system evaluated on unseen test data, and a detailed analysis of the dialogs assessing the viability of the approach.Comment: 13 pages, latex using aclap.st