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Jan O Pedersen - One of the best experts on this subject based on the ideXlab platform.
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a Temporal Comparison of altavista web searching
Journal of the Association for Information Science and Technology, 2005Co-Authors: Bernard J Jansen, Amanda Spink, Jan O PedersenAbstract:Major Web search engines, such as AltaVista, are essential tools in the quest to locate online information. This article reports research that used transaction log analysis to examine the characteristics and changes in AltaVista Web searching that occurred from 1998 to 2002. The research questions we examined are (1) What are the changes in AltaVista Web searching from 1998 to 2002? (2) What are the current characteristics of AltaVista searching, including the duration and frequency of search sessions? (3) What changes in the information needs of AltaVista users occurred between 1998 and 2002? The results of our research show (1) a move toward more interactivity with increases in session and query length, (2) with 70% of session durations at 5 minutes or less, the frequency of interaction is increasing, but it is happening very quickly, and (3) a broadening range of Web searchers' information needs, with the most frequent terms accounting for less than 1% of total term usage. We discuss the implications of these findings for the development of Web search engines.
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a Temporal Comparison of altavista web searching research articles
Journal of the Association for Information Science and Technology, 2005Co-Authors: Bernard J Jansen, Amanda Spink, Jan O PedersenAbstract:Major Web search engines, such as AltaVista, are essential tools in the quest to locate online information. This article reports research that used transaction log analysis to examine the characteristics and changes in AltaVista Web searching that occurred from 1998 to 2002. The research questions we examined are (1) What are the changes in AltaVista Web searching from 1998 to 2002? (2) What are the current characteristics of AltaVista searching, including the duration and frequency of search sessions? (3) What changes in the information needs of AltaVista users occurred between 1998 and 2002? The results of our research show (1) a move toward more interactivity with increases in session and query length, (2) with 70p of session durations at 5 minutes or less, the frequency of interaction is increasing, but it is happening very quickly, and (3) a broadening range of Web searchers' information needs, with the most frequent terms accounting for less than 1p of total term usage. We discuss the implications of these findings for the development of Web search engines. © 2005 Wiley Periodicals, Inc.
Roland Bobbink - One of the best experts on this subject based on the ideXlab platform.
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changes in species richness and composition in european acidic grasslands over the past 70 years the contribution of cumulative atmospheric nitrogen deposition
Global Change Biology, 2010Co-Authors: Cecilia Dupre, Carly J Stevens, Traute Ranke, A Bleeker, Cord Pepplerlisbach, David J G Gowing, Nancy B Dise, Edu Dorland, Roland BobbinkAbstract:Our study investigates the negative impact of nitrogen (N) deposition on species richness in acidic grasslands, based on a Temporal Comparison of vegetation data spanning a period of almost 70 years. We compiled a large data base of plots assigned to the Violion caninae grassland type, composed of managed, but unfertilized semi-natural grasslands on nutrient-poor, acidic soils. In total 1114 plots, mainly from Great Britain, the Netherlands and Germany, were compiled, dating back to 1939. Environmental site information included geographical and soil (mean Ellenberg values) variables as well as estimates of cumulative N and sulphur (S) deposition since 1939. Statistical analyses were carried out separately for the data subsets from the three regions. In all regions, the vegetation differentiation was mainly related to soil acidity and nutrient availability, as well as to the year of sampling and the cumulative amounts of N and S deposition. Plot-species richness of vascular plants and bryophytes (analysed for Great Britain only) decreased with time and analyses suggest these are affected by various factors, notably soil pH, but also latitude and cumulative N deposition. The latter explained more of the variation in species number than the year of sampling and cumulative S deposition, which supports the interpretation that the decline in species richness is mainly caused by increasing N availability and less by altered management and soil acidification. For Great Britain and Germany, cumulative N deposition showed a strong negative relationship with several biodiversity measures, especially the proportion of dicots, whereas it was positively related to the proportion of grass species. In general, our results give Temporal evidence for the negative effect of N deposition on species richness in semi-natural vegetation.
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changes in species richness and composition in european acidic grasslands over the past 70 years the contribution of cumulative atmospheric nitrogen deposition
Global Change Biology, 2010Co-Authors: Cecilia Dupre, Carly J Stevens, Traute Ranke, A Bleeker, Cord Pepplerlisbach, David J G Gowing, Nancy B Dise, Edu Dorland, Roland BobbinkAbstract:Our study investigates the negative impact of nitrogen (N) deposition on species richness in acidic grasslands, based on a Temporal Comparison of vegetation data spanning a period of almost 70 years. We compiled a large data base of plots assigned to the Violion caninae grassland type, composed of managed, but unfertilized semi-natural grasslands on nutrient-poor, acidic soils. In total 1114 plots, mainly from Great Britain, the Netherlands and Germany, were compiled, dating back to 1939. Environmental site information included geographical and soil (mean Ellenberg values) variables as well as estimates of cumulative N and sulphur (S) deposition since 1939. Statistical analyses were carried out separately for the data subsets from the three regions. In all regions, the vegetation differentiation was mainly related to soil acidity and nutrient availability, as well as to the year of sampling and the cumulative amounts of N and S deposition. Plot-species richness of vascular plants and bryophytes (analysed for Great Britain only) decreased with time and analyses suggest these are affected by various factors, notably soil pH, but also latitude and cumulative N deposition. The latter explained more of the variation in species number than the year of sampling and cumulative S deposition, which supports the interpretation that the decline in species richness is mainly caused by increasing N availability and less by altered management and soil acidification. For Great Britain and Germany, cumulative N deposition showed a strong negative relationship with several biodiversity measures, especially the proportion of dicots, whereas it was positively related to the proportion of grass species. In general, our results give Temporal evidence for the negative effect of N deposition on species richness in semi-natural vegetation.
Carly J Stevens - One of the best experts on this subject based on the ideXlab platform.
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changes in species richness and composition in european acidic grasslands over the past 70 years the contribution of cumulative atmospheric nitrogen deposition
Global Change Biology, 2010Co-Authors: Cecilia Dupre, Carly J Stevens, Traute Ranke, A Bleeker, Cord Pepplerlisbach, David J G Gowing, Nancy B Dise, Edu Dorland, Roland BobbinkAbstract:Our study investigates the negative impact of nitrogen (N) deposition on species richness in acidic grasslands, based on a Temporal Comparison of vegetation data spanning a period of almost 70 years. We compiled a large data base of plots assigned to the Violion caninae grassland type, composed of managed, but unfertilized semi-natural grasslands on nutrient-poor, acidic soils. In total 1114 plots, mainly from Great Britain, the Netherlands and Germany, were compiled, dating back to 1939. Environmental site information included geographical and soil (mean Ellenberg values) variables as well as estimates of cumulative N and sulphur (S) deposition since 1939. Statistical analyses were carried out separately for the data subsets from the three regions. In all regions, the vegetation differentiation was mainly related to soil acidity and nutrient availability, as well as to the year of sampling and the cumulative amounts of N and S deposition. Plot-species richness of vascular plants and bryophytes (analysed for Great Britain only) decreased with time and analyses suggest these are affected by various factors, notably soil pH, but also latitude and cumulative N deposition. The latter explained more of the variation in species number than the year of sampling and cumulative S deposition, which supports the interpretation that the decline in species richness is mainly caused by increasing N availability and less by altered management and soil acidification. For Great Britain and Germany, cumulative N deposition showed a strong negative relationship with several biodiversity measures, especially the proportion of dicots, whereas it was positively related to the proportion of grass species. In general, our results give Temporal evidence for the negative effect of N deposition on species richness in semi-natural vegetation.
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changes in species richness and composition in european acidic grasslands over the past 70 years the contribution of cumulative atmospheric nitrogen deposition
Global Change Biology, 2010Co-Authors: Cecilia Dupre, Carly J Stevens, Traute Ranke, A Bleeker, Cord Pepplerlisbach, David J G Gowing, Nancy B Dise, Edu Dorland, Roland BobbinkAbstract:Our study investigates the negative impact of nitrogen (N) deposition on species richness in acidic grasslands, based on a Temporal Comparison of vegetation data spanning a period of almost 70 years. We compiled a large data base of plots assigned to the Violion caninae grassland type, composed of managed, but unfertilized semi-natural grasslands on nutrient-poor, acidic soils. In total 1114 plots, mainly from Great Britain, the Netherlands and Germany, were compiled, dating back to 1939. Environmental site information included geographical and soil (mean Ellenberg values) variables as well as estimates of cumulative N and sulphur (S) deposition since 1939. Statistical analyses were carried out separately for the data subsets from the three regions. In all regions, the vegetation differentiation was mainly related to soil acidity and nutrient availability, as well as to the year of sampling and the cumulative amounts of N and S deposition. Plot-species richness of vascular plants and bryophytes (analysed for Great Britain only) decreased with time and analyses suggest these are affected by various factors, notably soil pH, but also latitude and cumulative N deposition. The latter explained more of the variation in species number than the year of sampling and cumulative S deposition, which supports the interpretation that the decline in species richness is mainly caused by increasing N availability and less by altered management and soil acidification. For Great Britain and Germany, cumulative N deposition showed a strong negative relationship with several biodiversity measures, especially the proportion of dicots, whereas it was positively related to the proportion of grass species. In general, our results give Temporal evidence for the negative effect of N deposition on species richness in semi-natural vegetation.
Jens Moller - One of the best experts on this subject based on the ideXlab platform.
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testing the dimensional Comparison theory when do students prefer dimensional Comparisons to social and Temporal Comparisons
Social Psychology of Education, 2018Co-Authors: Fabian Wolff, Friederike Helm, Jens MollerAbstract:Students compare their achievement in a subject with their classmates’ achievements (social Comparison), their own prior achievements (Temporal Comparison), and their achievements in other subjects (dimensional Comparison), which can each be better (upward Comparison), equal (lateral Comparison), or worse (downward Comparison). Prior research has investigated the impact of different Comparison motivations on the prevalence of social and Temporal Comparisons, but no study has examined the same for dimensional Comparisons yet. The present study closes this gap: A total of 605 German high school students were presented with four situations, in which a fictitious student receives the same objective feedback for an exam in a certain subject, but is motivated either to evaluate, to enhance, to improve, or to differentiate himself. For each Comparison motivation, the participants judged how likely the fictitious student was to draw dimensional, social, and Temporal upward, lateral, and downward Comparisons. As a central result, dimensional Comparisons in all directions had the highest prevalences under the self-differentiation motivation. In contrast, the prevalences of dimensional Comparisons were relatively low under the other three motivations. This finding complements the recently developed dimensional Comparison theory. For the first time, we could empirically show that dimensional Comparisons primarily serve self-differentiation motivations.
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the big three of comparative judgment on the effects of social Temporal and dimensional Comparisons on academic self concept
Social Psychology of Education, 2017Co-Authors: Hanno Mullerkalthoff, Friederike Helm, Jens MollerAbstract:Students evaluate their domain-specific abilities by comparing their own achievement in one domain to that of others (social Comparison), to their own previous achievement (Temporal Comparison), as well as their own achievement in another domain (dimensional Comparison). The theories underlying these three Comparison processes each assume an upward Comparison with a better-off standard to lead to lower self-concept and a downward Comparison with a worse-off standard to result in higher self-concept, instead. However, there is a lack of studies investigating the joint effects of simultaneously activated social, Temporal, and dimensional Comparisons. To close this gap, two experimental studies and one field study were conducted. In Studies 1 (N = 80) and 2 (N = 80), participants were asked to infer the mathematical self-concept of fictitious students after receiving experimentally manipulated social, Temporal, and dimensional information about the fictitious students’ achievement in mathematics. In Study 3 (N = 225), participants were asked to report their own mathematical self-concept after rating their mathematical achievement in Comparison to social, Temporal, and dimensional standards. In all three studies, similar main effects for each of the three Comparisons were found leading to lower self-concept following upward Comparisons and higher self-concept following downward Comparisons. Effect sizes differed, though, indicating social Comparisons to have the largest effect, whereas the effects of Temporal and dimensional Comparisons were small to medium sized. No interaction effects were found. The findings therefore indicate that all three Comparison processes are independent and have additive effects on academic self-concept.
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dimensional Comparison theory
Psychological Review, 2013Co-Authors: Jens Moller, Herbert W MarshAbstract:: Although social Comparison (Festinger, 1954) and Temporal Comparison (Albert, 1977) theories are well established, dimensional Comparison is a largely neglected yet influential process in self-evaluation. Dimensional Comparison entails a single individual comparing his or her ability in a (target) domain with his or her ability in a standard domain (e.g., "How good am I in math compared with English?"). This article reviews empirical findings from introspective, path-analytic, and experimental studies on dimensional Comparisons, categorized into 3 groups according to whether they address the "why," "with what," or "with what effect" question. As the corresponding research shows, dimensional Comparisons are made in everyday life situations. They impact on domain-specific self-evaluations of abilities in both domains: Dimensional Comparisons reduce self-concept in the worse off domain and increase self-concept in the better off domain. The motivational basis for dimensional Comparisons, their integration with recent social cognitive approaches, and the interdependence of dimensional, Temporal, and social Comparisons are discussed.
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paradoxical effects of praise and criticism social dimensional and Temporal Comparisons
British Journal of Educational Psychology, 2005Co-Authors: Jens MollerAbstract:Background. When developing a domain-specific academic self-concept, students are not restricted to social Comparisons; they may also make Temporal or dimensional Comparisons. Aims. The main purpose of this study was to examine whether these different types of Comparison trigger paradoxical effects of praise and criticism in the sense described by Meyer (1992). University students participated in Study 1 (N=120) and Study 4 (N=83). The Study 2 sample consisted of 180 seventh to ninth grade students, and Study 3 investigated paradoxical effects with a sample of 130 elementary school students. Methods. Participants were presented with vignettes describing the results of 2 students (social Comparison condition) versus 1 student in 2 subjects (dimensional Comparison) versus 1 student in 2 subsequent tests (Temporal Comparison). In all cases, the results were identical. Participants were then informed about a teacher's response to these results (praise vs. criticism vs. neutral response), and were asked to estimate the ability of the 2 stimulus persons. Results. Study 1 and Study 2 revealed that dimensional, as well as social, Comparisons following praise and criticism elicit paradoxical effects of perceived ability, reflected in corresponding estimations of student effort and teacher expectancies. There were no paradoxical effects following Temporal Comparisons. Study 3 did not reveal any paradoxical effects, thereby supporting the assumption that the occurrence of such effects depends on the level of cognitive development. Study 4 showed that the paradoxical effects found in Study 1 and 2 occur even when the sanctioned and the neutral achievement are presented independently. Conclusions. Dimensional Comparisons, which have been largely overlooked in the past, play a major role in ability inferences.
Bernard J Jansen - One of the best experts on this subject based on the ideXlab platform.
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a Temporal Comparison of altavista web searching
Journal of the Association for Information Science and Technology, 2005Co-Authors: Bernard J Jansen, Amanda Spink, Jan O PedersenAbstract:Major Web search engines, such as AltaVista, are essential tools in the quest to locate online information. This article reports research that used transaction log analysis to examine the characteristics and changes in AltaVista Web searching that occurred from 1998 to 2002. The research questions we examined are (1) What are the changes in AltaVista Web searching from 1998 to 2002? (2) What are the current characteristics of AltaVista searching, including the duration and frequency of search sessions? (3) What changes in the information needs of AltaVista users occurred between 1998 and 2002? The results of our research show (1) a move toward more interactivity with increases in session and query length, (2) with 70% of session durations at 5 minutes or less, the frequency of interaction is increasing, but it is happening very quickly, and (3) a broadening range of Web searchers' information needs, with the most frequent terms accounting for less than 1% of total term usage. We discuss the implications of these findings for the development of Web search engines.
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a Temporal Comparison of altavista web searching research articles
Journal of the Association for Information Science and Technology, 2005Co-Authors: Bernard J Jansen, Amanda Spink, Jan O PedersenAbstract:Major Web search engines, such as AltaVista, are essential tools in the quest to locate online information. This article reports research that used transaction log analysis to examine the characteristics and changes in AltaVista Web searching that occurred from 1998 to 2002. The research questions we examined are (1) What are the changes in AltaVista Web searching from 1998 to 2002? (2) What are the current characteristics of AltaVista searching, including the duration and frequency of search sessions? (3) What changes in the information needs of AltaVista users occurred between 1998 and 2002? The results of our research show (1) a move toward more interactivity with increases in session and query length, (2) with 70p of session durations at 5 minutes or less, the frequency of interaction is increasing, but it is happening very quickly, and (3) a broadening range of Web searchers' information needs, with the most frequent terms accounting for less than 1p of total term usage. We discuss the implications of these findings for the development of Web search engines. © 2005 Wiley Periodicals, Inc.
