Repeatability, correlation and path analysis of physical and chemical characteristics of peach fruits

This study aimed to determine the number of measurements necessary to evaluate physical and chemical characteristics of peach fruits, study the relationships between them and their direct and indirect effects on the content of ascorbic acid and total carotenoids. The characteristics skin and pulp color, fruit weight, suture, equatorial and polar diameters, firmness, soluble solids (SS), titratable acidity (TA), SS/TA ratio, ascorbic acid and total carotenoids were evaluated in 39 cultivars of peach and 3 cultivars of nectarine from the orchard of the Universidade Federal de Viçosa. The repeatability coefficient was estimated by ANOVA and CPCOR. Phenotypic correlation coefficients (rf) were estimated and, after the multicollinearity diagnostics, they were unfolded to direct and indirect effects of the explanatory variables on the response variable using path analysis. There was agreement on the magnitude of repeatability coefficients obtained by the two methods; however, they varied among the 14 characteristics. The highest correlations were found between FW, SD, ED and PD. Seven fruits are sufficient to evaluate the physical and chemical characteristics of peach with a correlation coefficient of 90%. The characteristics considered in the path diagrams (b* skin, hº skin, b* pulp, hº pulp, ED, PD, FIR, SS, SS/AT and TC) are not the main determinants of the ascorbic acid. The yellow hue of the pulp (hº pulp) has the potential to be used in indirect selection for total carotenoids.

Taloudellinen lisäarvo ja suhdanne-vaihtelut

Tutkimusongelmana oli ratkaista onko taloudellisella lisäarvolla ja suhdannevaihteluilla yhteyttä ja selittääkö suhdannevaihtelut taloudellisen lisäarvon vaihteluja. Empiirisenä aineistona oli 79 suomalaista pörssiyritystä, (kuljetus- ja huolinta, metalli- ja metsäteollisuus sekä auto- ja vähittäiskauppa). Tutkimusperiodina olivat vuodet 1986-2000. Tilastollisena tutkimusmenetelmänä oli regressioanalyysi, jossa selitettävänä muuttujana oli taloudellinen lisäarvo ja selittävänä muuttujana oli bruttokansantuoteprosentti. Analyysit tehtiin toimialamediaanina. Regressiomallin tulosten mukaan suhdannevaihtelut selittävät hyvin kuljetus- ja huolinta-alan yritysten taloudellisen lisäarvon vaihteluita. Metalliteollisuuden- ja autokaupan yritysten taloudelliset lisäarvot korreloivat jonkin verran suhdannevaihteluiden kanssa. Vähittäiskauppa ja metsäteollisuus eivät korreloineet suhdannevaihteluiden kanssa ollenkaan.

Young Firms and R&D subsidies in Catalonia

Based on four different public R&D calls from the Catalan government, this article evaluates the propensity of entrants and young firms to apply for R&D public grants and, as compared to their counterparts, their capacity for obtaining subsides. This analysis is particularly relevant since entrants and young firms encounter greater market difficulties. Our sample contains 22,139 firms and corresponds to a merge of two databases: one from the Catalan agency responsible for promoting private innovation (ACC1Ó) and the other from the Mercantile Register. Merging these databases has two advantages. Firstly, participants and non-participants in the public R&D call (“InnoEmpresa”) are included and, secondly, it provides us with information at firm and project level. The period of observation is between 2006 and 2010, since some explanatory variables are lagged by one period. We apply a two-step methodology. Our results show that entrants and young firms show a lower propensity to apply for R&D subsidies and to obtain R&D public grants. Firm size, exports and participation in a previous call show a positive impact on the likelihood of applying, and firms located in the Barcelona metropolitan area have a greater propensity to apply. Additionally, project quality and R&D cooperative reports presented jointly with other partners have a positive impact on the likelihood of obtaining the R&D subsidy. Finally, firms that have previously obtained an R&D subsidy do not exhibit a greater propensity for obtaining subsequent grants. Keywords: R&D subsidies, entrants and young firms Classification JEL: L53, L25, O38

Online and Offline Participation at the Local Level : A Quantitative Analysis of the Catalan Municipalities

This paper presents a first analysis on local electronic participatory experiences in Catalonia. The analysis is based on a database constructed and collected by the authors. The paper carries out an explanatory analysis of local initiatives in eparticipationand off line participation taking into account political variables (usually not considered in this kind of analysis) but also classical socio-economic variables that characterise municipalities. Hence, we add a quantitative analysis to the numerous case studies on local e-participation experiences. We have chosen Catalonia because is one of the European regions with more initiatives and one that has enjoyed considerable local governmental support to citizen participation initiatives since the 80s. The paper offers a characterisation of these experiences and a first explanatory analysis, considering: i) the institutional context in which these experiences are embedded, ii) the characteristics of the citizen participation processes and mechanisms on-line, and iii) a set of explanatory variables composed by the population size, thepolitical adscription of the mayor, the electoral abstention rate, age, income and level ofeducation in the municipality. The model that we present is explanatory for the municipalities with more than 20,000 inhabitants but it is not for the fewer than 20,000inhabitants. Actually, the number of participatory activities developed by these last municipalities is very low. Among all the variables, population size becomes the mostinfluential variable. Political variables such as political party of the mayor and the localabstention rate have a certain influence but that have to be controlled by population size.

Ecological and physiological variance in T-cell mediated immune response in Cory's shearwaters

T-cell mediated immune response (CMI) hasbeen widely studied in relation to individual andfitness components in birds. However, few studieshave simultaneously examined individual and socialfactors and habitat-mediated variance in theimmunity of chicks and adults from the samepopulation and in the same breeding season. Weinvestigated ecological and physiological variancein CMI of male and female nestlings and adults in abreeding population of Cory's Shearwaters(Calonectrisdiomedea) in theMediterranean Sea. Explanatory variables includedindividual traits (body condition, carbon andnitrogen stable isotope ratios, plasma totalproteins, triglycerides, uric acid, osmolarity,β-hydroxy-butyrate, erythrocyte meancorpuscular diameter, hematocrit, andhemoglobin) and burrow traits(temperature, isolation, and physicalstructure). During incubation, immune responseof adult males was significantly greater than thatof females. Nestlings exhibited a lower immuneresponse than adults. Ecological and physiologicalfactors affecting immune response differed betweenadults and nestlings. General linear models showedthat immune response in adult males was positivelyassociated with burrow isolation, suggesting thatmales breeding at higher densities suffer immunesystem suppression. In contrast, immune response inchicks was positively associated with bodycondition and plasma triglyceride levels.Therefore, adult immune response appears to beassociated with social stress, whereas a trade-offbetween immune function and fasting capability mayexist for nestlings. Our results, and those fromprevious studies, provide support for anasymmetrical influence of ecological andphysiological factors on the health of differentage and sex groups within a population, and for theimportance of simultaneously considering individualand population characteristics in intraspecificstudies of immune response.

Ecological and physiological variance in T-cell mediated immune response in Cory's shearwaters

T-cell mediated immune response (CMI) hasbeen widely studied in relation to individual andfitness components in birds. However, few studieshave simultaneously examined individual and socialfactors and habitat-mediated variance in theimmunity of chicks and adults from the samepopulation and in the same breeding season. Weinvestigated ecological and physiological variancein CMI of male and female nestlings and adults in abreeding population of Cory's Shearwaters(Calonectrisdiomedea) in theMediterranean Sea. Explanatory variables includedindividual traits (body condition, carbon andnitrogen stable isotope ratios, plasma totalproteins, triglycerides, uric acid, osmolarity,β-hydroxy-butyrate, erythrocyte meancorpuscular diameter, hematocrit, andhemoglobin) and burrow traits(temperature, isolation, and physicalstructure). During incubation, immune responseof adult males was significantly greater than thatof females. Nestlings exhibited a lower immuneresponse than adults. Ecological and physiologicalfactors affecting immune response differed betweenadults and nestlings. General linear models showedthat immune response in adult males was positivelyassociated with burrow isolation, suggesting thatmales breeding at higher densities suffer immunesystem suppression. In contrast, immune response inchicks was positively associated with bodycondition and plasma triglyceride levels.Therefore, adult immune response appears to beassociated with social stress, whereas a trade-offbetween immune function and fasting capability mayexist for nestlings. Our results, and those fromprevious studies, provide support for anasymmetrical influence of ecological andphysiological factors on the health of differentage and sex groups within a population, and for theimportance of simultaneously considering individualand population characteristics in intraspecificstudies of immune response.

Local privatization, intermunicipal cooperation, transaction costs and political interests: Evidence from Spain

Several empirical studies have analyzed the factors that influence local privatization. Variables related to fiscal stress, cost reduction, political processes and ideological attitudes are the most common explanatory variables used in these studies. In this paper, we add to this literature by examining the influence of transaction costs and political factors on local governments’ choices through new variables. In addition to this, we consider the role of additional aspects, such as intermunicipal cooperation as a potential alternative to privatization in order to exploit scale economies or scope economies. We consider two relevant services: solid waste collection and water distribution. Results from our estimates show that privatization (that is, contracting out to a private firm) is less common for water distribution than for solid waste collection. Higher transaction costs in water distribution are consistent with this finding. Furthermore, we find that municipalities with a conservative ruling party privatize more often regardless of the ideological orientation of the constituency. This shows that those political interests able to influence local elections are more important in determining the form of delivery than is the basic ideological stance of the constituency. Finally, we find that intermunicipal cooperation is an alternative to local privatization.

Social capital and health : variations, associations and challenges

Although social capital and health have been extensively studied during the last decade, there are still open issues in current empirical research. These concern for instance the measurement of the concept in different contexts, as well as the association between different types of social capital and different dimensions of health. The present thesis addressed these questions. The general aim was to promote the understanding of social capital and health by investigating the oldest old and the two major language groups in Finland, Swedish- and Finnish-speakers. Another aim was to contribute to the discussion on methodological issues in social capital and health research. The present thesis investigated two empirical data sets, Umeå 85+ and Health 2000. The Umeå 85+ study was a cross-sectional study of 163 individuals aged 85, 90, and 95 or older, living in the municipality of Umeå, Sweden, in the year of 2000. The Health 2000 survey was a national study of 8,028 persons aged 30 or above carried out in Finland in 2000-2001. Different indicators of structural (e.g. social contacts) and cognitive (e.g. trust) social capital, as well as health indicators were used as variables in the analyses. The Umeå 85+ data set was analyzed with factor analysis, as well as univariate and multivariate analysis of variance. The Health 2000 data was analyzed with logistic regression techniques. The results showed that the Swedish-speakers in the Finnish data set Health 2000 had consistently higher prevalence of social capital compared to the Finnish-speakers even after controlling for central sociodemographic variables. The results further showed that even if the language group differences in health were small, the Swedishspeakers experienced in general better self-reported health compared with the Finnish-speakers. Common sociodemographic variables could not explain these observed differences in health. The results imply that social capital is often, but not always, associated with health. This was clearly seen in the Umeå 85+ data set where only one health indicator (depressive symptoms) was associated with structural social capital among the oldest old. The results based on the analysis of the Health 2000 survey demonstrated that the cognitive component of social capital was associated with self-rated health and psychological health rather than with participation in social activities and social contacts. In addition, social capital statistically reduced the health advantage especially for Swedish-speaking men, indicating that high prevalence of social capital may promote health. Finally, the present thesis also discussed the issue of methodological challenges faced with when analyzing social capital and health. It was suggested that certain components of social capital such as bonding and bridging social capital may be more relevant than structural and cognitive components when investigating social capital among the two language groups in Finland. The results concerning the oldest old indicated that the structural aspects of social capital probably reflect current living conditions, whereas cognitive social capital reflects attitudes and traits often acquired decades earlier. This is interpreted as an indication of the fact that structural and cognitive social capital are closely related yet empirically two distinctive concepts. Taken together, some components of social capital may be more relevant to study than others depending on which population group and age group is under study. The results also implied that the choice of cut-off point of dichotomization of selfrated health has an impact on the estimated effects of the explanatory variables. When the whole age interval, 35-64 years, was analyzed with logistic regression techniques the choice of cut-off point did not matter for the estimated effects of marital status and educational level. The results changed, however, when the age interval was divided into three shorter intervals. If self-rated health is explored using wide age intervals that do not account for age-dependent covariates there is a risk of drawing misleading conclusions. In conclusion, the results presented in the thesis suggest that the uneven distribution of social capital observed between the two language groups in Finland are of importance when trying to further understand health inequalities that exist between Swedish- and Finnish-speakers in Finland. Although social capital seemed to be relevant to the understanding of health among the oldest old, the meaning of social capital is probably different compared to a less vulnerable age group. This should be noticed in future empirical research. In the present thesis, it was shown that the relationship between social capital and health is complex and multidimensional. Different aspects of social capital seem to be important for different aspects of health. This reduces the possibility to generalize the results and to recommend general policy implementations in this area. An increased methodological awareness regarding social capital as well as health are called for in order to further understand the cfomplex association between them. However, based on the present data and findings social capital is associated with health. To understand individual health one must also consider social aspects of the individuals’ environment such as social capital.

Price spike forecasting in a competitive day-ahead energy market

Electricity price forecasting has become an important area of research in the aftermath of the worldwide deregulation of the power industry that launched competitive electricity markets now embracing all market participants including generation and retail companies, transmission network providers, and market managers. Based on the needs of the market, a variety of approaches forecasting day-ahead electricity prices have been proposed over the last decades. However, most of the existing approaches are reasonably effective for normal range prices but disregard price spike events, which are caused by a number of complex factors and occur during periods of market stress. In the early research, price spikes were truncated before application of the forecasting model to reduce the influence of such observations on the estimation of the model parameters; otherwise, a very large forecast error would be generated on price spike occasions. Electricity price spikes, however, are significant for energy market participants to stay competitive in a market. Accurate price spike forecasting is important for generation companies to strategically bid into the market and to optimally manage their assets; for retailer companies, since they cannot pass the spikes onto final customers, and finally, for market managers to provide better management and planning for the energy market. This doctoral thesis aims at deriving a methodology able to accurately predict not only the day-ahead electricity prices within the normal range but also the price spikes. The Finnish day-ahead energy market of Nord Pool Spot is selected as the case market, and its structure is studied in detail. It is almost universally agreed in the forecasting literature that no single method is best in every situation. Since the real-world problems are often complex in nature, no single model is able to capture different patterns equally well. Therefore, a hybrid methodology that enhances the modeling capabilities appears to be a possibly productive strategy for practical use when electricity prices are predicted. The price forecasting methodology is proposed through a hybrid model applied to the price forecasting in the Finnish day-ahead energy market. The iterative search procedure employed within the methodology is developed to tune the model parameters and select the optimal input set of the explanatory variables. The numerical studies show that the proposed methodology has more accurate behavior than all other examined methods most recently applied to case studies of energy markets in different countries. The obtained results can be considered as providing extensive and useful information for participants of the day-ahead energy market, who have limited and uncertain information for price prediction to set up an optimal short-term operation portfolio. Although the focus of this work is primarily on the Finnish price area of Nord Pool Spot, given the result of this work, it is very likely that the same methodology will give good results when forecasting the prices on energy markets of other countries.

Hallintoelinten oikeudenmukainen palkitseminen - toimialavertailu osuustoiminnallisissa organisaatioissa

Työn tarkoituksena oli lähteä tutkimaan palkitsemisen, vaativuuden ja tehtävien eroavaisuuksia kolmen osuustoiminnallisen organisaation hallintoelinten välillä. Tavoitteena oli selvittää, miten palkitsemisen horisontaalista oikeudenmukaisuutta voitaisiin kehittää osuustoiminnallisten organisaatioiden hallintoelimissä. Tutkimus toteutettiin kvantitatiivisena kyselylomaketutkimuksena, ja analysointimenetelmänä käytettiin regressioanalyysiä. Tutkimuksen teoreettinen viitekehys koostui palkitsemisesta ja sen oikeudenmukaisuudesta keskittyen horisontaaliseen ulottuvuuteen, työn vaativuudesta sekä aiempien tutkimusten perusteella palkitsemiseen vaikuttavista tekijöistä muun muassa rakenteen, toimialan ja strategian näkökulmista. Tutkimuksessa havaittiin, että tilaajaorganisaatiossa X palkkiot olivat vertailuorganisaatiota Y ja Z korkeammat. Erot vaativuuden ja tehtävien osalta eivät olleet yhtä suuria kuin palkkioissa, mutta organisaatiossa X nämäkin olivat pääasiassa korkeammalla tasolla. Regressioanalyysissä kävi ilmi, että työn vaativuus selittää suurimman osan palkitsemisen kertymästä ja muut tilastollisesti merkittävät selittävät muuttujat olivat huomattavasti vähäisempiä. Organisaation X korkeamman palkkiotason voitiin nähdä johtuvan erilaisesta palkkiorakenteesta sekä siitä, että se otti palkitsemisessa organisaation koon huomioon; palkkiot vaihtelivat huomattavasti enemmän alueorganisaatioiden kesken kuin organisaatiossa Y ja Z. Johtopäätöksenä voidaan sanoa, että työn vaativuusarviointi palkkioiden horisontaalista oikeudenmukaisuutta arvioitaessa on merkittävimmässä asemassa. Muiden tarkasteltujen muuttujien osalta tulokset eivät olleet aivan odotetun kaltaisia tai täysin yhdenmukaisia aiempien tutkimusten kanssa, vaikka samansuuntaisiakin havaintoja saatiin. Työn tärkein anti oli kuitenkin työn vaativuusarvioinnin tärkeyden havaitseminen hallintoelintyön palkitsemisen yhteydessä horisontaalisella tasolla.

Characteristics of urban heat island (UHI) in a high latitude coastal city - a case study of Turku, SW Finland

The term urban heat island (UHI) refers to the common situation in which the city is warmer than its rural surroundings. In this dissertation, the local climate, and especially the UHI, of the coastal city of Turku (182,000 inh.), SW Finland, was studied in different spatial and temporal scales. The crucial aim was to sort out the urban, topographical and water body impact on temperatures at different seasons and times of the day. In addition, the impact of weather on spatiotemporal temperature differences was studied. The relative importance of environmental factors was estimated with different modelling approaches and a large number of explanatory variables with various spatial scales. The city centre is the warmest place in the Turku area. Temperature excess relative to the coldest sites, i.e. rural areas about 10 kilometers to the NE from the centre, is on average 2 °C. Occasionally, the UHI intensity can be even 10 °C. The UHI does not prevail continuously in the Turku area, but occasionally the city centre can be colder than its surroundings. Then the term urban cool island or urban cold island (UCI) is used. The UCI is most common in daytime in spring and in summer, whereas during winter the UHI prevails throughout the day. On average, the spatial temperature differences are largest in summer, whereas the single extreme values are often observed in winter. The seasonally varying sea temperature causes the shift of relatively warm areas towards the coast in autumn and inland in spring. In the long term, urban land use was concluded to be the most important factor causing spatial temperature differences in the Turku area. The impact was mainly a warming one. The impact of water bodies was emphasised in spring and autumn, when the water temperature was relatively cold and warm, respectively. The impact of topography was on average the weakest, and was seen mainly in proneness of relatively low-lying places for cold air drainage during night-time. During inversions, however, the impact of topography was emphasised, occasionally outperforming those of urban land use and water bodies.

Patient and physician evaluation of the severity of acute asthma exacerbations

We studied the ability of patients not experienced in the use of peak expiratory flow meters to assess the severity of their asthma exacerbations and compared it to the assessment of experienced clinicians. We also evaluated which data of physical examination and medical history are used by physicians to subjectively evaluate the severity of asthma attacks. Fifty-seven adult patients (15 men and 42 women, with a mean (± SD) age of 37.3 ± 14.5 years and 24.0 ± 17.9 years of asthma symptoms) with asthma exacerbations were evaluated in a University Hospital Emergency Department. Patients and physicians independently evaluated the severity of the asthma attack using a linear scale. Patient score, physician score and forced expiratory volume at the first second (FEV1) were correlated with history and physical examination variables, and were also considered as dependent variables in multiple linear regression models. FEV1 correlated significantly with the physician score (rho = 0.42, P = 0.001), but not with patient score (rho = 0.03; P = 0.77). Use of neck accessory muscles, expiratory time and wheezing intensity were the explanatory variables in the FEV1 regression model and were also present in the physician score model. We conclude that physicians evaluate asthma exacerbation severity better than patients and that physician's scoring of asthma severity correlated significantly with objective measures of airway obstruction (FEV1). Some variables (the use of neck accessory muscles, expiratory time and wheezing intensity) persisted as explanatory variables in physician score and FEV1 regression models, and should be emphasized in medical schools and emergency settings.

Yhdysvaltalaisten matkustajalentoyhtiöiden rahoituksellisen lentopolttoaineen hintasuojautumisen kustannusvaikutukset 2000-luvulla

Tämän kandidaatintutkielman tarkoituksena on tutkia, miten yhdysvaltalaisten lentoyhtiöiden harjoittama rahoituksellinen lentopolttoaineen hintasuojaus on vaikuttanut niiden keskimääräisiin polttoainekustannuksiin 2000-luvun aikana. Lisäksi tavoitteena on kirjallisuuskatsauksen muodossa tarkastella lentopolttoaineen hintariskiä ja siltä suojautumista. Aiheeseen liittyvä aiempi tutkimus on pääasiassa keskittynyt rahoitusasemaan liittyvien vaikutusten tarkasteluun. Tässä tutkielmassa puolestaan tutkitaan suojauksen vaikutusta tarkasteltavien lentoyhtiöiden liiketoiminnan kustannuksiin. Lentopolttoaineen hintasuojauksen kustannusvaikutuksia arvioidaan regressiomallilla, jossa selitettävänä muuttujana on lentoyhtiön keskimääräinen polttoainekustannus. Selittävinä muuttujina puolestaan toimivat seuraavan vuoden arvioiduista polttoainehankinnoista rahoituksellisin keinoin suojattujen hankintojen osuus sekä lentopolttoaineen keskimääräinen markkinahinta kunakin tarkasteluvuonna. Tutkimuksen aineisto koostuu kymmenestä yhdysvaltalaisesta lentoyhtiöstä ja niiden 2000-luvulla vuosikertomuksissaan raportoimista tiedoista liittyen polttoainekustannuksiin ja rahoitukselliseen polttoaineen hintasuojaukseen. Lisäksi lentopolttoaineen keskimääräiset vuotuiset markkinahinnat tarkastelujakson ajalta haetaan Yhdysvaltain energiainformaatiota välittävän viranomaisen verkkotietokannasta. Johtopäätöksenä todetaan yhdysvaltalaisten lentoyhtiöiden rahoituksellisen polttoaineen hintasuojauksen vähentäneen niiden keskimääräisiä polttoainekustannuksia 2000-luvun aikana. Lentopolttoaineen markkinahinnan todetaan vaikuttavan kustannuksiin reilusti lentoyhtiöiden suojaustoimenpiteitä voimakkaammin. Lisäksi aiempiin tutkimuksiin ja toisaalta tässä tutkielmassa estimoitavan mallin autokorreloituvaan luonteeseen nojaten todetaan, että tämän mallin selittävät muuttujat eivät ole ainoat keskimääräisiin polttoainekustannuksiin vaikuttavat tekijät. Yhteenvetona todetaankin tarkempaa lisätutkimusta tarvittavan, jotta tämän tutkielman tulokset voidaan luotettavammin yleistää.

Functional Forms and Educational Production Functions

Different Functional Forms Are Proposed and Applied in the Context of Educational Production Functions. Three Different Specifications - the Linerar, Logit and Inverse Power Transformation (Ipt) - Are Used to Explain First Grade Students' Results to a Mathematics Achievement Test. with Ipt Identified As the Best Functional Form to Explain the Data, the Assumption of Differential Impact of Explanatory Variables on Achievement Following the Status of the Student As a Low Or High Achiever Is Retained. Policy Implications of Such Result in Terms of School Interventions Are Discussed in the Paper.

Projection-Based Statistical Inference in Linear Structural Models with Possibly Weak Instruments

It is well known that standard asymptotic theory is not valid or is extremely unreliable in models with identification problems or weak instruments [Dufour (1997, Econometrica), Staiger and Stock (1997, Econometrica), Wang and Zivot (1998, Econometrica), Stock and Wright (2000, Econometrica), Dufour and Jasiak (2001, International Economic Review)]. One possible way out consists here in using a variant of the Anderson-Rubin (1949, Ann. Math. Stat.) procedure. The latter, however, allows one to build exact tests and confidence sets only for the full vector of the coefficients of the endogenous explanatory variables in a structural equation, which in general does not allow for individual coefficients. This problem may in principle be overcome by using projection techniques [Dufour (1997, Econometrica), Dufour and Jasiak (2001, International Economic Review)]. AR-types are emphasized because they are robust to both weak instruments and instrument exclusion. However, these techniques can be implemented only by using costly numerical techniques. In this paper, we provide a complete analytic solution to the problem of building projection-based confidence sets from Anderson-Rubin-type confidence sets. The latter involves the geometric properties of “quadrics” and can be viewed as an extension of usual confidence intervals and ellipsoids. Only least squares techniques are required for building the confidence intervals. We also study by simulation how “conservative” projection-based confidence sets are. Finally, we illustrate the methods proposed by applying them to three different examples: the relationship between trade and growth in a cross-section of countries, returns to education, and a study of production functions in the U.S. economy.