In the relatively sparse field of economics of prostitution, studies have in recent years investigated the relationship between prostitution legislation and the presence of sex trafficking. This study investigates the issue further by using both a cross country model with time fixed effects and a country fixed effect model to estimate the effect on the amount of sex trafficking of changing legislation to the so-called Nordic Model, something no other known study has managed to do. In contrast to what previous research has estimated, this thesis finds no significant effect on sex trafficking from changing legislation to the Nordic Model. The obvious difficulties of presenting reliable data on an illegal activity such as sex trafficking and the fact that few countries have changed their legislation to the Nordic Model are likely reasons to the insignificant results and cautions against a causal interpretation.

Do estate and neighborhood characteristics influence perceptions of safety? Using data from a survey of residents living in municipal housing in Gothenburg, this paper argues that the spatial and social characteristics of a neighborhood vastly outpace the role of its socioeconomic and demographic composition, when it comes to accounting for the perceived safety of its residents. The dataset consists of survey data on residents’ perception of safety from 2013-2014 and 2016-2021 in Gothenburg linked with sociodemographic data at an estate level. This allows us to examine the effects of neighborhood and estate characteristics on perceived safety. We compare two different indices of safety and conceptualize safety as residential safety, which is then analyzed using statistical models. The study employs a combined estate and year fixed effect model with estate clustering and robust standard errors to strengthen the causal identification between the relationships and the robustness of the results. The study finds strong support for neighborhoods’ social and spatial characteristics such as contact with neighbors and the level of streetlights to influence individuals’ perception of safety. Weaker support is also established for the safety level to be affected by the socioeconomic composition in the area and the estate. These findings indicate that the social cohesion in a neighborhood and the spatial organization are important factors in increasing residential safety.

This thesis investigates whether players in the National Hockey League overperform during the last year of their contract. This phenomenon is called the contract year phenomenon and suggests that players have financial incentives to perform better during this specific season. Previous research has shown evidence of this phenomenon in the National Basketball Association and some evidence in Major League Baseball. To investigate this we have used data from 6 season in the NHL between 2016 to 2022. A linear regression was conducted to identify the relationship between points per hour and contract year. A negative relationship between the variables were identified, probably due to the fact that worse players tend to sign shorter contracts, getting a contract year more often. When fixed effect regression was conducted to compare individual players with themselves over time, no significant relationship between the variables was observed, indicating that there is no evidence of the contract year phenomenon in the NHL. The non existing effect remains when looking at specific contract statuses and position in combination with the contract year variable.

Aim: The aim of this study was to investigate if there is a beneficial effect on the prevalence of white spot lesions (WSL) in the mandibular and maxillary teeth when the teeth in the maxilla are treated with fluoride varnish compared to a placebo group. The null hypothesis was that there is no difference between the test and placebo group in development of WSL. Material and Method: 182 patients from three clinics in Scania county (Sweden) undergoing treatment with fixed orthodontic appliances were selected to participate, in the end 149 patients were included in the study. The patients were divided into two groups, one receiving a varnish of 7700 ppm fluoride (Fluor Protector S, Ivoclar Vivadent AG, Schaan, Liechtenstein) and one a placebo varnish. Pre- and post-treatment photos were taken and WSL was graded according to Gorelick index by two independent observers.  Results: No significant difference could be seen between the test and placebo group, neither on surface nor individual level. The results were based on both t-test and percentual calculations.  Conclusion: The null hypothesis could be accepted since no significant difference could be seen between the test or placebo group. Due to the loss of a number of patients, mainly because of loss in the original study and new exclusion criteria set by the authors, the results may have been conflicted. More research is therefore needed to draw any conclusions. / Syfte: Syftet med studien var att undersöka om det finns en effekt på förekomsten av white spot lesions (WSL) hos under- och överkäkens tänder när tänderna i överkäken behandlas med fluoridvarnish. Nollhypotesen sattes till att det inte finns någon skillnad mellan test- och placebogruppen i prevalens av WSL. Material och metod: Patienter från tre olika kliniker i Skåne deltog i studien, 149 av 182 deltagare fullföljde studien. Patienterna delades in i två grupper, en som fick ett fluoridvarnish med 7700 ppm fluorid (Fluor Protector S, Ivoclar Vivadent AG, Schaan, Liechtenstein) och en med placebovarnish. Kliniska foton togs innan samt efter behandling med fast apparatur som graderades och bedömdes enligt Gorelick-skalan för WSL av två oberoende observatörer. Resultat: Det fanns ingen signifikant skillnad mellan testgruppen och placebogruppen varken på individ- eller ytnivå. Resultatet baserades på både t-test och procentberäkningar. Slutsats: Nollhypotesen accepterades då ingen signifikant skillnad fanns mellan test- och placebogrupp. På grund av bortfall av patienter, både i originalstudien men även med anledning av exklusionskriterier satta för denna studie, kan resultatet ha påverkats. Mer forskning behövs därför för att dra några slutsatser.

Långtidsarbetslöshet har i Sverige sedan mitten av 1990-talet varit en återkommande och omdebatterad politisk fråga. För att arbeta med problemet har det sedan dess fokuserats på en aktiv arbetsmarknadspolitik innehållandes åtgärder som arbetsmarknadspolitiska program, utbildningar samt subventionerade anställningar. Sedan 2006 har nyttjandet avsubventionerade anställningar ökat i Sverige. Nystartsjobben som infördes 2007 är en subventionerad anställningsform med syfte att stimulera arbetsgivare att anställa personer med en längre tids frånvaro från arbetsmarknaden. Arbetsgivare får med nystartsjobb en kreditering av arbetsgivaravgiften när de anställt en långtidsarbetslös person. Att subventionerade anställningar har en mekanism som ger en positiv effekt på flödet från långtidsarbetslöshet till anställning har påvisats i ett antal studier. Resultaten är dock varierande och då olika subventioner skiljer sig åt i utformningen är det svårt att få en entydig bild. Denna uppsats har studerat vilken påverkan nystartsjobben har på långtidsarbetslösheten. Med paneldata över Sveriges 290 kommuner observerade mellan 2007–2019 och en regressionsanalys med fixa effekter som metod, har studien besvarat frågeställningen: ”Minskar nystartsjobben långtidsarbetslösheten?” Kontrollvariabler som inkluderas i regressionen är andel personer i övriga subventionerade anställningar, vakanser, utbildning samt andel äldre och yngre. Resultaten visar att när andelen i nystartsjobb ökar, minskar långtidsarbetslösheten. Effekten av andel personer i nystartsjobb på andel långtidsarbetslösa visar ett estimat på -0,329% då kontrollvariablerna är mätta ett år innan andel långtidsarbetslösa. Det tolkas som att vid en procentenhets ökning av andel i nystartsjobb ses i genomsnitt en minskning av andel långtidsarbetslösa med 0,329 procentenheter. Med detta konstateras slutligen att studiens resultat visat på att det finns en totaleffekt på långtidsarbetslösheten av nystartsjobben, men den är inte markant / Long-term unemployment has since the mid 90´s been a recurring political question in Sweden. The issue has been dealt with through the usage of active labor market policies, such as different labor market programs, vocational education and training and subsidized employment. Since 2006, the usage of subsidized employments in Sweden has increased. New-start-jobs, a subsidized employment with the purpose to invigorate employers to hire long-term unemployed persons were introduced in 2007. It gives the employer a tax relief when hiring a person who has been unemployed for a certain period of time. Previous research has shown that subsidized employments have a positive effect on the flow from long term unemployment to employment. However, the results vary and since many subsidies differ in their design it is complicated to get an unambiguous answer. This thesis has examined what impact the new-start-jobs have on the long-term unemployment rate. The purpose has been to answer the question “Does the new-start-jobs reduce long-term unemployment?” The method used in the study is a fixed effect regression model using panel data of Sweden’s 290 municipalities during the period 2007-2019. The results indicate that when the proportion of people in new-start-jobs increase, the long term unemployment rate decreases. Control variables have been included and consists of proportion of individuals in other subsidized employments, vacancies, education, share of older and younger people in the population. The estimated effect of share of people in new start-jobs on long-term unemployment in the working age population is -0,329%, when the control variables is lagged one year. The result in this study means that one percentage pointincrease in the proportion of people participating in new-start-jobs, on average decreases the proportion of long-term unemployed with 0,329 percentage points. With that result established, an effect is seen, but it is not particularly strong.

No description available.

No description available.

Linear mixed models are frequently used to analyze data with random effects and/or repeated measures. A common approach to such analyses requires choosing a covariance structure. Information criteria, such as AIC and BIC, are often used by statisticians to help with this task. However, these criteria do not always point to the true covariance structure and therefore the wrong covariance structure is sometimes chosen. Once this step is complete, Wald statistics are used to test fixed effects. Degrees of freedom for these statistics are not known. However, there are approximation methods, such as Kenward and Roger (KR) and Satterthwaite (SW) that have been shown to work well in some situations. Schaalje et al. (2002) concluded that the KR method would perform at least as well as or better than the SW method in many cases assuming that the covariance structure was known. On the other hand, Keselman et al. (1999) concluded that the performance of the SW method when the covariance structure was selected using AIC was poor for negative pairings of treatment sizes and covariance matrices and small sample sizes. Our study used simulations to investigate Type I error rates in test of fixed effects using Wald statistics with the KR adjustment method, incorporating the selection of the covariance structure using AIC and BIC. Performance of the AIC and BIC criteria in selecting the true covariance structure was also studied. The MIXED procedure (SAS v. 9) was used to analyze each simulated data set. Type I error rates from the best AIC and BIC models were always higher than target values. However, Type I error rates obtained by using the BIC criterion were better than those obtained by using the AIC criterion. Type I error rates for the correct models were often adequate depending on the sample size and complexity of covariance structure. Performance of AIC and BIC was poor. This could be a consequence of small sample sizes and the high number of covariance structures these criteria had to choose from.

Anaerobic digestion is a process where biogas is generated from organic substance in the absence of oxygen. The most common application of the anaerobic digestion technology in developing countries is small-scale household digesters producing biogas for cooking purposes. These systems are usually fed with cattle dung or organic household waste. The typical small-scale digester models are fixed-dome digester, floating-drum digester and rubber-balloon digester. Biogas systems contribute to self-sustainability of energy production, improve waste management and mitigate deforestation and health problems caused by poor waste management and usage of traditional cooking fuels such as firewood and charcoal. Anaerobic digestion technology is still quite unknown in Mozambique. An initiative to implement this technology in the municipality of Quelimane located in Zambézia province in the central part of the country, was taken in 2015 and background studies were performed during spring 2015 and 2016. As a part of the study resulting in this report, performed in spring 2017, a small-scale biogas digester was installed in Quelimane city. The digester was fed with the initial input of cow manure in order to create population of anaerobic bacteria and in the future it’s planned to be fed with food waste. The purpose of the first installed digester is to serve for educational purposes and to produce cooking fuel for the few people working in the municipal location where the digester is installed. It’s estimated that the digester has a potential to produce daily 0.3 m3 of biogas from 2 kg of food waste which can be used for preparing lunch for the employees or for heating water. In the future, possible applications of anaerobic digestion technology in Quelimane are a municipal biogas plant, cooling systems for the fish industry and biogas based latrines in the less developed areas located outside of the city center.

Till följd av att större delen av alla nyproducerade bostadsrätter i Stockholms kommun idag säljs till fasta priser är det intressant att undersöka och ta reda på varför inte fler bostadsproducenter använder sig av budgivning som försäljningsstrategi. Hur dessa fasta priser fastställs av bostadsproducenterna och vad som ligger till grund för den bedömningen, är även det en intressant aspekt.  Information som ligger till grund för de teoretiska utgångspunkterna har inhämtats genom en grundlig litteraturstudie. Resultatet bygger på ett par kvalitativa intervjuer för att ta reda på vilka parametrar som spelar in vid val av försäljningsstrategi och prissättning. Urvalet av intervjukandidater har noga övervägts och landade i en aktör som använder sig av ett budgivningsförfarande och en aktör som använder sig av fast pris som försäljningsstrategi, för att på bästa sätt kunna ställa dessa metoder mot varandra.  Analysen visar bland annat att storleken på projektet, vilka finansieringsalternativ som är möjliga, inställningen och egenskaperna hos bostadsproducenterna och hur marknadsläget råder är avgörande för vilken strategi som används. Slutsatsen mynnar ut i att mycket handlar om finansieringsmässig trygghet och att det är en inställningsfråga hos bostadsproducenterna. Det finns därmed goda möjligheter att i större utsträckning använda sig av budgivning som försäljningsstrategi. Alternativt att kombinera de två olika metoderna, budgivning och fast pris, för att på så sätt nå maximal avkastning, vilket borde ligga i bostadsproducentens intresse. / Due to the fact that most new production of condominiums in the municipality of Stockholm today are sold at fixed prices, it is interesting to investigate and find out why not more real estate developers use bidding as a sales strategy. How these fixed prices are determined by the developers and the basis for that assessment. Information that underlies the theoretical starting points has been obtained through a thorough literature study. The result is based on a couple of qualitative interviews to find out which parameters are involved in choosing a specific sales strategy and pricing. The selection of interview candidates has been carefully considered and landed in an actor using a bidding process and an actor using fixed price as a sales strategy. The analysis shows, among other things, that the size of the project, which financing options that are possible, the attitude of condominium developers and how the market situation prevails determines the strategy used. The conclusion is that the attitude among the real estate developers plays a big role, and there are good opportunities to make more use of bidding as a sales strategy. Alternatively, combine the two different methods, bidding and fixed price, in order to achieve maximum return.