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

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

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

Optimized utilization of Salix-Perspectives for the genetic improvement toward sustainable biofuel value chains

Bioenergy will be one of the most important renewable energy sources in the conversion from fossil fuels to bio-based products. Short rotation coppice Salix could be a key player in this conversion since Salix has rapid growth, positive energy balance, easy to manage cultivation system with vegetative propagation of plant material and multiple harvests from the same plantation. The aim of the present paper is to provide an overview of the main challenges and key issues in willow genetic improvement toward sustainable biofuel value chains. Primarily based on results from the research project "Optimized Utilization of Salix" (OPTUS), the influence of Salix wood quality on the potential for biofuel use is discussed, followed by issues related to the conversion of Salix biomass into liquid and gaseous transportation fuels. Thereafter, the studies address genotypic influence on soil carbon sequestration in Salix plantations, as well as on soil carbon dynamics and climate change impacts. Finally, the opportunities for plant breeding are discussed using willow as a resource for sustainable biofuel production. Substantial phenotypic and genotypic variation was reported for different wood quality traits important in biological (i.e., enzymatic and anaerobic) and thermochemical conversion processes, which is a prerequisite for plant breeding. Furthermore, different Salix genotypes can affect soil carbon sequestration variably, and life cycle assessment illustrates that these differences can result in different climate mitigation potential depending on genotype. Thus, the potential of Salix plantations for sustainable biomass production and its conversion into biofuels is shown. Large genetic variation in various wood and biomass traits, important for different conversion processes and carbon sequestration, provides opportunities to enhance the sustainability of the production system via plant breeding. This includes new breeding targets in addition to traditional targets for high yield to improve biomass quality and carbon sequestration potential

Marknad som marknad? – En studie om fondförvaltares prestation på olika marknader

Svenskar har en stor andel av sina sparpengar placerade i olika fonder, och fondsparande verkar bli en allt större sparform. Under andra kvartalet 2014 ökade den totala förmögenheten i svenskregistrerade fonder med 69 miljarder gentemot föregående kvartal, vilket går att tolka som att det är väldigt populärt att spara i fonder. Denna studie undersöker fonder vars förvaltare har kontor i Sverige och vad som kan tänkas påverka dennes prestation. För att göra detta har fyra aspekter valts ut och de är geografiskt avstånd, marknadens grad av sofistikering, storleken på bolag samt persistens. För att genomföra undersökningen kategoriserades de valda fonderna i grupper utifrån dessa aspekter. Därefter gjordes statistiska tester för att se om prestationen skiljde sig åt mellan grupperna. Tre olika mått på prestation användes för att få en mer nyanserad bild av prestationen. De är den vanliga avkastningen, Treynorkvoten och Modigliani-Modigliani. Om marknaden vore starkt effektiv borde inte de valda variablerna ha någon inverkan på förvaltarens prestation. Med andra ord bör de utförda testen inte visa någon statistisk signifikant skillnad. Resultaten visar att marknaden är delvis effektiv, men att den i vissa avseenden inte är det. Gällande det geografiska avståndet och storleksskillnaden var resultaten tydliga, att marknaden inte varit effektiv ur de aspekterna. Även resultaten angående persistensen visade på signifikanta resultat att förvaltare har presterat bättre än valt jämförelseindex under vissa perioder. Det som motsäger detta, och som konfirmerar den effektiva marknaden, är resultaten från marknadens sofistikering som inte påvisar någon signifikant skillnad mellan grupperna. Syftet med denna uppsats var att se om det finns incitament för att spara i och att förvalta aktiva fonder. Då resultaten visar att marknaden inte har varit fullt effektiv i alla avseenden finns det incitament för aktiv fondförvaltning

Delaktighet som pedagogik och demokratiskt värde för fullföljandet av studier - kunskapsbidrag från ett utvecklingsprojekt

Participation as a pedagogy and democratic value turns out to be a critical element in students’ completion of school. Completed education is a regional development project in which a survey has been conducted in order to identify successful strategies to promote completed education in school. In an analysis, in the context of the survey, with an emphasis on school and participation as a pedagogy and democratic value, several findings are shown. It turns out that the importance of participation manifests itself through an emphasis on the societal and democratic mission of school; school ethos; the value praxis of school; pedagogical approach; and viewing the pupil as capable. It is, in more detail, shown that it is particularly crucial to understand the completion of education in school as a pedagogical problem; create sustainable institutional structures not bound to one person; and to make sure that students are participants in their own education.Utbildning och lärande. Tidskrift</p

Hög tid för riskidentifiering : när bank- och försäkringsbolag migrerar sina lokala applikationer till molnet

Bank- och försäkringsbolag på den svenska marknaden frångår sina traditionella lokala applikationer och har påbörjat den stora migreringen till molnet. Många svårigheter behöver tas i beaktande och syftet med den här studien var därför att bidra med kunskap kring vilka risker som kan identifieras till själva migreringen av lokala applikationer till molnmiljö. Nio semistrukturerade intervjuer genomfördes på respondenter i olika organisatoriska roller, på olika företag, med insikt och kunskap om migreringens risker från olika perspektiv. Materialet analyserades sedan abduktivt. Studien bekräftar tidigare identifierade risker inom litteraturen och identifierar två nya risker. Bland totalt nio identifierade risker var risker relaterade till informationssäkerhet, förlorad åtkomst till data, kompetens, det finansiella samt juridik och regelefterlevnad de mest framträdande. Studien avslutas med förslag för framtida forskning.Banking and insurance companies in the Swedish market are moving away from their traditional local applications and have started the big migration to the cloud. Many difficulties need to be considered and the purpose of this study was therefore to contribute with knowledge about which risks can be identified to the execution of moving local applications to a cloud environment. Nine semi-structured interviews were conducted on respondents in different organizational roles, at different companies, with insight and knowledge of the risks of migration from different perspectives. The material was then analyzed abductively. The study confirms risks identified by previous research and identifies two new risks. Among a total of nine identified risks, risks related to information security, lost access to data, competence, the financial, and legal and regulatory compliance were the most prominent. The study concludes with suggestions for future research

Delaktighet som pedagogik och demokratiskt värde för fullföljandet av studier - kunskapsbidrag från ett utvecklingsprojekt

Participation as a pedagogy and democratic value turns out to be a critical element in students’ completion of school. Completed education is a regional development project in which a survey has been conducted in order to identify successful strategies to promote completed education in school. In an analysis, in the context of the survey, with an emphasis on school and participation as a pedagogy and democratic value, several findings are shown. It turns out that the importance of participation manifests itself through an emphasis on the societal and democratic mission of school; school ethos; the value praxis of school; pedagogical approach; and viewing the pupil as capable. It is, in more detail, shown that it is particularly crucial to understand the completion of education in school as a pedagogical problem; create sustainable institutional structures not bound to one person; and to make sure that students are participants in their own education.Utbildning och lärande. Tidskrift</p

Kommunikationsstilar och kulturell intelligens i globala virtuella team : en kvalitativ studie om effektiv kommunikation

Syftet med den här uppsatsen är att få en bättre förståelse för hur olika kommunikationsstilarkommer till uttryck i en kontext av globala virtuella team (GVT), genom att undersöka vad deinnebär för teamets effektiva kommunikation. Därutöver undersöks även vilken roll kulturellintelligens (CQ) spelar i sammanhanget. För att granska ämnet har en kvalitativ metodbestående av semistrukturerade intervjuer och Critical Incident Technique använts.Intervjuerna inkluderade medlemmar tillhörande ett GVT från SSAB, såväl som enskildaindivider som arbetar i GVT i andra företag. Resultatet visar att olika kommunikationsstilarinom ett GVT kan leda till missförstånd och därmed hindra den effektiva kommunikationen.Resultatet visar också att CQ kan hjälpa till att minska missförstånd i GVT. The purpose of this study is to gain a deeper understanding of how different communicationstyles manifest in the context of global virtual teams (GVT), which is done by looking atwhat they entail for the teams effective communication. In addition to this, the role of culturalintelligence (CQ) in the context is also being explored. To examine this topic, this studyapplied a qualitative method consisting of semi-structured interviews and Critical IncidentTechnique. The interviews conducted included the members of a GVT from the companySSAB, as well as unrelated employees working in GVTs from other companies. The resultsdemonstrate that different communication styles in GVTs can lead to misunderstandings andtherefore hinder effective communication. The results also show that CQ can help reducemisunderstandings in GVTs