Bakgrund: Filmklimatet har gjort det svårt för producenter att nå lönsamhet och fånga en stor biopublik. Under 2014 var det 78 % av svensk film som gick med förlust. Filmbranschen har genomgått stora förändringar till följd av digitaliseringen, där den nya tekniken har resulterat i en stor flexibilitet som har medfört att biograferna snabbare kan svara på biopublikens efterfrågan. Filmer kan numera snabbt plockas bort från biorepertoaren. Det har resulterat i att gapet mellan filmer som går bra och filmer som går dåligt har ökat. Aktörer talar om en bransch som präglas av turbulens, osäkerhet och risktagande, där den primära inkomstkällan för producenter är intäkter som genereras från bio. Producenters strategiska val blir allt viktigare för en films överlevnad.  Syfte: Studiens syfte är att undersöka vilka strategiska val en producent kan använda sig av för att en film ska erhålla höga intäkter och nå lönsamhet. Metod: Studien använder sig av en kvantitativ metod som utgår från en deduktiv ansats där 111 filmer har studerats genom regressionsanalyser.  Resultat: Studien har identifierat att budget och huvudrollsinnehavare påverkar en films intäkter. Det går det inte att urskilja vilka strategier som leder till att en film blir lönsamhet.

Today's society is characterized by consumption and consumers are offered endless amount of choices. This has developed thanks to society's susceptibility to consumption. Market competition is increasing constantly, which forces companies to evolve more and more in order to get a good knowledge of the consumer. A committed company can adapt and develop different marketing strategies using the knowledge of consumer behavior, thereby acting as a competitive tool that strengthens their market position. Products that brings forth a certain behavior of the consumer, such that the consumer will be prone to spend more time in searching information, refers to as high involvement products. During the decision making process, the consumer can be influenced by everything from past experience to perception of personality. The study is designed using only primary data and the survey is based on open interviews with five consumers who have made a purchase of a high involvement product within the last month. With the help of theories and previous research, the collected data analyses some of the different factors that can influence the consumers during the consumer buying decision process of a high involvement product. A clear connection can be found between consumer buying decision process and the different characteristics which are reflected in the study's theory chapter. The most recurrent attributes that the consumers have been affected by the purchase decision process first step, appear to be also upcoming in the following stages. The most frequent factor, as consumers proved most affected by are groups. Primary groups, in the form of parents, family members and friends, returning several times at all of those asked consumers purchase decision process. The reason can be that the feeling of trust from the costumer’s side is higher in the primary groups, while there may exist lack of trust for retailers as they may seem to act for company or personal gain.

Current research suggests schools face many barriers in effectively monitoring student's response to behavioral interventions in the classroom. The purpose of this study was to evaluate the FastBridge - Direct Behavior Rating (FastBridge-DBR), a brief, novel progress monitoring measure, designed to assess student behavioral change in response to a classroom behavioral intervention. Twenty-four elementary teacher-student dyads implemented a daily progress report intervention to promote positive student behavior during pre-specified classroom activities. FastBridge-DBR data were then collected for three target behaviors (i.e., Academic Engagement, Disruptive Behavior, Withdrawal) and compared to Systematic Direct Observation (SDO) data. Five change metrics (i.e., absolute change, percent of change from baseline, improvement rate difference, Tau-U, effect size; Gresham, 2005) were used to examine sensitivity to change. The Usage Rating Profile - Assessment (URP-A) was used to evaluate teacher acceptability of FastBridge-DBR. FastBridge-DBR scores were highly correlated with SDO data, demonstrating evidence of concurrent validity. FastBridge-DBR change metrics were significantly correlated with SDO change metrics. Additionally, while teachers provided high acceptability ratings for FastBridge-DBR, there was a lack of association between teachers' ratings of acceptability and student behavioral change. Implications for practice, study limitations, and areas of future research are discussed.

Firms developing new products often face the challenge of making investment decisions under uncertain input-cost conditions due to the price volatilities of the materials they use. These decisions need to be made long before the final products are launched on the market. Therefore, firms who invest in the opportunity to switch materials in a timely manner will have the flexibility to react to material price changes and realize competitive advantages. However, volatile material prices may also cause a firm to delay investment. Using real-options reasoning, this article studies the influence of input-cost fluctuations on the timing decision to start new product development (NPD) and thus create the follow-on opportunity to later replace an existing product. A model that combines waiting and switching options to derive influencing factors of the flexibility value which triggers the investment is developed and tested on a sample of material substitution projects from manufacturing firms. The results show how price uncertainty of the new and the old material, their joint price development, the expected project duration, and competitive preemption are related to the propensity to delay the start of NPD. The findings provide new insights on how timing in adopting materials can be used to hedge exposure to volatile material prices. The insights are relevant for adopters and producers of new materials, as well as for policy makers who strive for supporting the diffusion of new materials. (authors' abstract)

The real estate market in Sweden in the current situation is found to be very attractive, which in return is influenced by number of elements such as interest rates, market conditions, etc. Real estate investments result in relatively large amounts, that is why investors like to be relatively sure regarding their investments, or at least that they are knowing to get their investment back in case of a sale. Real options are a complement to the calculation real estate companies does. Real options are used to take alternative solutions in regard, and also to contribute alternative values to the investment, which is mainly used if an investments outcome is not as desired. As a result to this complement to the calculation we wished to study the following: What can influence the application of real options in a real estate investing decision in private real estate companies? This study was done with a deductive method, and because of that a theoretical reference frame were formed, and afterwords investigate if the theoretical facts agreed with reality. To be able to compare the theoretical parts and the empirical parts, it was important that the empirical part was relevant to our subject. For the empirical fact to be as relevant as possible, this study was performed with a qualitative approach, and therefor four private real estate companies were interviewed, two bigger and two smaller. The real estate companies interviewed are active in the southern parts of Sweden. This study results in four conclusions drawn on the basis of the four interviewed real estate companies, regarding what can influence the application of real options in a investment decision. Three of the real estate companies finds that the risks with commercial real estates, and the external factors which influence market conditions affect their application of alternative solutions regarding their investments. All four of the real estate companies find that new incoming information and the experience, which the decision maker holds, affects application of real options. Thus, real estate companies must be able to know when and what alternative solutions to apply. / Fastighetsmarknaden i Sverige anses vara väldigt attraktiv i dagsläget, vilket flertalet faktorer bidrar till såsom ränteläge, marknadsförhållanden etcetera. Investeringar i fastigheter medför relativt stora belopp, därför tenderar investerare att vilja vara relativt säkra på sina investeringar, eller att de åtminstone kan få tillbaka den erlagda investeringen vid en eventuell försäljning. Ett komplement till de kalkyler fastighetsbolagen genomför är reala optioner. Reala optioner används för att ta alternativa lösningar i beaktan, samt för att kunna tillföra investeringen alternativa värden, vilket främst används om investeringen inte har ett önskat utfall. Detta komplement till kalkyler medförde att vi önskade undersöka; vad kan påverka tillämpningen av reala optioner vid beslut om fastighetsinvesteringar i privata fastighetsbolag? Studien genomfördes med en deduktiv metod, vilket medförde att en teoretisk referensram sammanställdes för att därefter undersöka om teorierna överensstämde med verkligheten. För att kunna jämföra de teoretiska bidragen med empirisk data gällde det att den empiriska informationen var relevant. För att det empiriska materialet skulle bli så relevant som möjligt är studien genomförd enligt en kvalitativ ansats, där fyra privata fastighetsbolag intervjuades, två större och två mindre. Fastighetsbolagen delades in i respektive grupp efter storleken efter deras fastighetsbestånd. De olika fastighetsbolagen är verksamma i stora delar av södra Sverige. Studien resulterade i att vi kom fram till fyra slutsatser dragna utifrån de fyra intervjuade fastighetsbolagen, angående vad som kan påverka reala optioners tillämpning vid investeringsbeslut. Tre av fastighetsbolagen ansåg att riskerna som kommersiella fastigheter har, samt de yttre faktorer som påverkar marknadsförhållandena spelar in på deras tillämpning av alternativa lösningar på sina investeringar. Alla fyra fastighetsbolagen ansåg att ny information som tillkommer och erfarenheten som beslutsfattaren besitter påverkar tillämpningen av reala optioner. Således är fastighetsbolagens förmåga att veta om vilka alternativa lösningar som kan tillämpas och när viktiga.

Many online learning technologies grant students great autonomy and control, which imposes high demands for self-regulated learning (SRL) skills. With the fast development of online learning technologies, helping students acquire SRL skills becomes critical to student learning. Theories of SRL emphasize that making problem selection decisions is a critical SRL skill. Research has shown that appropriate problem selection that fit with students’ knowledge level will lead to effective and efficient learning. However, it has also been found that students are not good at making problem selection decisions, especially young learners. It is critical to help students become skilled in selecting appropriate problems in different learning technologies that offer learner control. I studied this question using, as platform, a technology called Intelligent Tutoring Systems (ITSs), a type of advanced learning technology that has proven to be effective in supporting students’ domain level learning. It has also been used to help students learn SRL skills such as help-seeking and self-assessment. However, it is an open question whether ITS can be designed to support students’ learning of problem selection skills that will have lasting effects on their problem selection decisions and future learning when the tutor support is not in effect. ITSs are good at adaptively selecting problems for students based on algorithms like Cognitive Mastery. It is likely, but unproven, that ITS problem selection algorithms could be used to provide tutoring on students’ problem selection skills through features like explicit instructions and instant feedback. Furthermore, theories of SRL emphasize the important role of motivations in facilitating effective SRL processes, but not much prior work in ITS has integrated designs that could foster the motivations (i.e., motivational design) to stimulate and sustain effective problem selection behaviors. Lastly, although students generally appreciate having learner control, prior research has found mixed results concerning the effects of learner control on students’ domain level learning outcomes and motivation. There is need to investigate how learner control over problem selection can be designed in learning technologies to enhance students’ learning and motivation. My dissertation work consists of two parts. The first part focuses on creating and scaffolding shared student/system control over problem selection in ITSs by redesigning an Open Learner Model (OLM, visualizations of learning analytics that show students’ learning progress) and integrating gamification features to enhance students’ domain level learning and enjoyment. I conducted three classroom experiments with a total of 566 7th and 8th grade students to investigate the effectiveness of these new designs. The results of the experiments show that an OLM can be designed to support students’ self-assessment and problem selection, resulting in greater learning gains in an ITS when shared control over problem selection is enabled. The experiments also showed that a combination of gamification features (rewards plus allowing re-practice of completed problems, a common game design pattern) integrated with shared control was detrimental to student learning. In the second part of my dissertation, I apply motivational design and user-centered design techniques to extend an ITS with shared control over problem selection so that it helps students learn problem selection skills, with a lasting effect on their problem selection decisions and future learning. I designed a set iv of tutor features that aim at fostering a mastery-approach orientation and learning of a specific problem selection rule, the Mastery Rule. (I will refer to these features as the mastery-oriented features.) I conducted a fourth classroom experiment with 200 6th – 8th grade students to investigate the effectiveness of shared control with mastery-oriented features on students’ domain level learning outcomes, problem selection skills and enjoyment. This experiment also measured whether there were lasting effects of the mastery-oriented shared control on students’ problem selection decisions and learning in new tutor units. The results of the experiment show that shared control over problem selection accompanied by the mastery-oriented features leads to significantly better learning outcomes, as compared to full system-controlled problem selection in the ITS. Furthermore, the mastery-oriented shared control has lasting effects on students’ declarative knowledge of problem selection skills. Nevertheless, there was no effect on future problem selection and future learning, possibly because the tutor greatly facilitated problem selection (through its OLM and badges). My dissertation contributes to the literatures on the effects of learner control on students’ domain level learning outcomes in learning technologies. Specifically, I have shown that a form of learner control (i.e., shared control over problem selection, with mastery-oriented features) can lead to superior learning outcomes than system-controlled problem selection, whereas most prior work has found results in favor of system control. I have also demonstrated that Open Learner Models can be designed to enhance student learning when shared control over problem selection is provided. Further, I have identified a specific combination of gamification features integrated with shared control that may be detrimental to student learning. A second line of contributions of my dissertation concerns research on supporting SRL in ITSs. My work demonstrates that supporting SRL processes in ITSs can lead to improved domain level learning outcomes. It also shows that the shared control with mastery-oriented features have lasting effects on improving students’ declarative knowledge of problem selection skills. Regarding using ITSs to help students learn problem selection skill, the user-centered motivational design identifies mastery-approach orientation as important design focus plus tutor features that can support problem selection in a mastery-oriented way. Lastly, the dissertation contributes to human-computer interaction by generating design recommendations for how to design learner control over problem selection in learning technologies that can support students’ domain level learning, motivation and SRL.

Bakgrund: Förvirringen kring hur den ideella sektorn och dess mångfald ska benämnas försvårar situationen gällande hur forskning om sektorn utvecklas. Fokus i denna studie är därför enbart på välgörenhetsorganisationer, som en del av den ideella sektorn. Antalet välgörenhetsorganisationer tycks ständigt öka och som följd har en slags konkurrenssituation utvecklats, vilket har ökat organisationernas medvetenhet kring styrning. Givare och allmänhet förväntar sig allt mer tydlighet och transparens vad gäller information om organisationernas prestationer och resultat. Problemdiskussion: Välgörenhetsorganisationer står inför ett antal utmaningar vad gäller deras styrning. Utmaningarna tycks bero på att beslutsfattandet uppfattas som diffust och otydligt samt att det saknas definitioner och mått av väsentliga begrepp så som prestationer och resultat. Funderingar har väckts kring hur organisationernas beslut om resursprioriteringar görs och vilken roll och påverkan ekonomistyrning har vid dessa situationer. Vidare har funderingar även väckts angående prestationsoch resultatbegreppets innebörd i välgörenhetsorganisationers specifika kontext. Syfte: Studiens första syfte är att kartlägga välgörenhetsorganisationernas beslutsprocess för att identifiera och förklara hur beslut om resursprioriteringar görs och vilken roll ekonomistyrningen har vid dessa beslutssituationer. Vidare syftar studien även till att definiera prestationsbegreppet och hur detta kan mätas samt utreda vad resultatbegreppet innebär för välgörenhetsorganisationer. Studien ska resultera i en referensram för att öka kunskapen om ekonomistyrningens roll i välgörenhetsorganisationers beslutsprocess. Metod: Forskningen antar en fallstudie med två välgörenhetsorganisationer där semi-strukturerade intervjuer och granskning av dokument har legat till grund för insamling av empiriskt material. Resultat och analys: Ekonomistyrningen tycks inte ha den roll eller det genomslag i de studerade organisationerna som den beskrivs kan eller till och med borde ha, detta tycks vidare kunna bero på ett antal identifierade gap. Besluten i organisationerna tycks istället påverkas och styras av en rad andra faktorer, där medlemmarnas tolkning av dessa faktorer uppfattas som utbredd. I dagsläget använder sig organisationerna inte av begreppet prestation utan talar istället i andra termer när de syftar på vad de utför. Resultatbegreppet tycks vidare ha två innebörder beroende på situationen. Slutsats: Utifrån studien som genomförts kan det konstateras att ekonomistyrningen inte har en speciellt utbredd roll i välgörenhetsorganisationernas verksamhet och inte heller i deras beslutsprocess. Besluten tenderar istället att baseras på medlemmarnas känslor, interna diskussioner, extern information, tillströmningen av medel och vad som är publikt för tillfället. Organisationerna talar i termer av output, aktivitet och verksamhet när de syftar till begreppet prestation. Vidare innebär prestationsbegreppet att något utförts, vanligen gentemot mottagaren i utsatthet. Det har dock uppdagats att organisationerna utför prestationer av både social och ekonomisk karaktär. Resultatbegreppet tycks vidare avgöra värdeaspekten i det som organisationerna utför. Resultatbegreppet i organisationerna syftar därmed som följd både till ekonomiska och sociala resultat. / Background: The confusion around how the nonprofit sector and its diversity will be named complicates the situation regarding how research about the sector develops. Focus of this study is therefore solely on charities, as a part of the nonprofit sector. The amounts of charities are constantly increasing and as a consequence a competitive situation has occurred, which has increased the organizations awareness about management control. Donors and the public are expecting even more clarity and transparency regarding information about the organizations performance and results. Problem discussion: Charities face a number of challenges regarding their management control. The challenges seem to be related to the fact that the decision-making is perceived as diffuse and unclear. Also lacks of definitions and measures around significant concepts like performance and results. Concerns have been raised about how the organizations' decisions on resource prioritizations are done and what role and impact management control has in these situations. Furthermore, concerns have also been raised regarding the concepts of performance and results and their signification in the charities specific context. Purpose: The first objective of the study is to map the charitable organization's decision-making process. This in order to identify and explain how decisions about resource priorities are made and what role the management control has on these decision-making situations. Secondly, the study aims to define the concept of performance and how the concept of performance can be measured and also examine what the concept of result means for charities. The study will result in a framework for increasing knowledge about the role of management control in the decision-making process of charities. Method: This research adopts a case study methodology with two charities in which semi-structured interviews and reviews of documents have been the basis for collecting empirical data. Results and analysis: The management control does not appear to have the role or the impact of the studied organizations that it is described can or even should have, which seem to depend on a number of identified gaps. The decisions of the organizations seem rather to be influenced and controlled by a number of other factors, where the members' interpretation of these factors is perceived as widespread. In the current situation the organisations are not using the concept of performance, instead they are talking in other terms when they refer to what they do. The concept of result seems furthermore have two meanings depending on the situation. Conclusion: Based on the study conducted, it can be stated that the management control does not have a particularly prevalent role in the charitable organizations and not either in their decision-making process. Instead, the decisions tend to depend on the members' feelings, internal discussions, external information, the inflow of funds and what is currently of public interest. The organizations are talking in terms of output, activity, and operation when they refer to the concept of performance. Furthermore, the concept of performance means that something has been done, usually against the receiver in distress. However, it has been revealed that the organizations are undertaking performance of both social and economic character. The concept of result also seems to determine the value of what the organizations accomplish. The concept of result, as a consequence, therefore aims both to economic and social results.

This thesis explores how multi-agent-based simulation can be used for transport policy analysis. Transport policies are often used as a means to reach governmental goals, such as environmental targets to reduce the impact of transportation. To predict how transportation is influenced by policies, public authorities often make use of simulation models. A structured review of such models is made focussing on important transport chain characteristics. We argue that to properly predict the actual environmental, economic, and logistical effects of transport policies, the logistical decisions made in transport chains must be modelled appropriately. Such decisions, e.g., concern the choice of producer and traffic mode, planning of transportation, production, and terminal handling. The review concludes that models currently used for transport policy analysis fail to capture many of these characteristics. We argue that agent-based models have the potential to include these aspects since they are able to explicitly model the actual decision making in transport chains. We have identified a set of generic roles in transport chains where each role is responsible for certain decisions. A multi-agent-based simulator, TAPAS, has been developed in which these roles are modelled as agents. Thus, the decision making in transport chains and its influence by the application of transport policies are captured. The decisions lead to the execution of the logistical operations which in turn have consequences on the logistics, economic, and environmental performance. The usage of TAPAS is illustrated by presenting two scenarios based on realworld transport chains. Simulation experiments of the scenarios have been performed where different types of transport policies are introduced. The simulation results are analysed, e.g., by comparing the results to similar studies and by sensitivity analysis of input parameters. To facilitate the validation and generalisation of simulation results we suggest making use of typical transport chains and roles characterised by, e.g., product type and geographical locations. The type of studies that TAPAS can support are described and compared to studies typically made with traditional models. Transport policies which are relevant to examine are described and their potential influence on transport chains are analysed. The possible usage of TAPAS is discussed and related to different types of users. Public authorities can, e.g., use TAPAS to complement studies using traditional models. This can improve the accuracy of the simulation results by the inclusion of more logistical aspects. Large companies are another type of user which, e.g., can use TAPAS to analyse new market segments, such as new product types or new consumers, where historical data is not available.

A cursory review of domestic apparel production data from ‘Cotton Counts Its Customers’ reports by The National Cotton Council of America showed a discrepancy between the amounts of cotton utilized in domestically produced women’s apparel and that for men’s apparel. It appeared that the men’s apparel sector had a higher percentage market share of cotton than women’s apparel. For both genders, cotton’s dwindling market share was similar to that of diminishing domestic US apparel production overall. Since the majority of apparel in the U.S. is imported, import data was obtained from the United States International Trade Commission and compiled with the domestic apparel data to offer a more expansive view of cotton’s market share and its use separated by gender. The compilation of domestic and import apparel data followed the overall trend of a higher percentage of weight of cotton being used in men’s apparel than in women’s. Challenging apparel categories which may offer potential for expanded utilization with increased performance were Coats, Underwear/Nightwear, Suits, and Dresses. In an attempt to add context to the apparel market data, we explored two stages of the apparel supply chain: the first at the retail setting, the second at the consumer purchase and wear decision level. At the retail level, we investigated the availability of fiber composition information and its use as a part of the assortment offered to consumers. Two stores were selected for this exploratory phase and retail availability by gender and fiber content were physically tallied in the two retail settings. In both retail assortments, there was no emphasis of fiber composition as part of the information offered to the consumer. For the consumer wanting to find cotton apparel in these two settings, prior knowledge regarding the feel or look of cotton would seem necessary to facilitate locating cotton among the assortment of apparel. Fiber blends can offer cotton-like appearance and hand, so fiber composition tags could give consumers certainty regarding the garments they are buying. In addition to the observations above, we also noted in both stores a prevalence of cotton in men’s apparel, and a larger presence of man-made fibers in women’s apparel, which reflects the overall market situation. Finally, the second exploratory stage focused on clothing diaries and a wardrobe inventory provided by a small purposeful sample of respondents to examine the role of fiber composition, cotton in particular, in the individual’s garment purchase and daily-use decisions. The findings suggested that fiber composition was an important part of the daily garment selection process, based upon the daily activity and a set of personal beliefs about what the diary respondent felt that fiber had to offer. Similar to the market data Results, in the Clothing Diary responses males showed a greater tendency to select both 100% cotton Tops and Bottoms than did the female respondents. Overall, cotton appeared challenged by man-made and other fibers when the respondents needed to “dress up”, to attend to athletic activity, or to satisfy the need for specific functionalities such as rapid drying. / text

Ce travail est dédié à l'étude du comportement agrégatif chez la fourmi Lasius niger afin de caractériser le phénomène au niveau collectif, par l'étude de la dynamique et de la structure agrégative, et au niveau des mécanismes sous-tendant le phénomène par l’analyse des comportements individuels des fourmis. Nous avons montré expérimentalement et vérifié par la modélisation que l’agrégation est essentiellement liée à un phénomène amplificateur : plus l’agrégat est de grande taille, plus les fourmis y restent longtemps. Nos résultats indiquent que le niveau d’agrégation et la structure formée sont dépendants de plusieurs facteurs comme la densité et la surface disponible : une évolution de la structure agrégative des nourrices est observée, passant d’un grand agrégat stable pour les petites densité-surface à plusieurs agrégats à hiérarchie de taille moins marquée pour les grandes densité-surface. L’agrégation est aussi influencée par la caste éthologique des fourmis, les nourrices s’agrégeant en un agrégat stable de grande taille, les fourrageuses en quelques petits agrégats instables. Cette différence s’explique par une probabilité plus faible des fourrageuses à rester dans l’agrégat. Dans les groupes mixtes, les fourmis gardent les caractères propres à leur caste, ne semblant pas influencées par la caste de l’individu rencontré. Enfin, l’agrégation diffère quantitativement mais non qualitativement selon l’espèce utilisée : nos études sur Crematogaster scutellaris, Atta sexdens-rubropilosa, Solenopsis invicta, Pheidole pallidula, Linepithema humile, Myrmica rubra et M. ruginodis montrent une grande variété de réponses, en nombre et en taille d’agrégats, qui est aussi fonction de la caste de fourmis utilisée. Une constance, cependant, apparaît dans nos résultats : les nourrices paraissent mieux s’agréger que les fourrageuses. Ces résultats sont discutés en fonction de leur valeur adaptative pour la colonie et d’un lien possible avec la distribution spatiale des individus à l’intérieur du nid./This work is dedicated to the study of the aggregative behaviour in the ant Lasius niger in order to characterize the phenomenon at the collective level by a study of the dynamic and the collective structure, and at the individual level to understand the mechanisms underlying the phenomenon. We demonstrated experimentally and verified by a model that aggregation is essentially due to an amplificatory phenomenon: the greater the ant numbers in a cluster, the greater the time spent by an ant inside this cluster. Our results indicate that the aggregation level and the form of the collective structure depend on different factors such as the density and the surface: for brood-tenders, an evolution of the aggregative structure is observed shifting from a large stable aggregate for low density-surface to several smaller clusters with a less pronounced hierarchical size for the greater density-surface. Aggregation is also influenced by the ethological caste of the ant: the brood-tenders aggregate in a big stable cluster and the foragers in some unstable clusters. This difference is explained by a smaller probability of foragers to stay inside the cluster. In mixed groups, ants keep their own characteristics, not appearing to be influenced by the caste of the individual encountered. Finally, aggregation is influenced by the ant species: our studies on Crematogaster scutellaris, Atta sexdens-rubropilosa, Solenopsis invicta, Pheidole pallidula, Linepithema humile, Myrmica rubra and M. ruginodis show us a large variety of responses, in the number and the size of the clusters, which is also a function of the caste of ants which is used. A constant result, nevertheless, appears in our results: brood-tenders seem to aggregate better than foragers. These results are discussed in term of their adaptive value for the colony and a possible link with the spatial distribution of ants inside the nest.