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Set Size (set + size)
Selected AbstractsRanked Set Sampling: Cost and Optimal Set SizeBIOMETRICS, Issue 4 2002Ramzi W. Nahhas Summary. Mclntyre (1952, Australian Journal of Agricultural Research3, 385,390) introduced ranked set sampling (RSS) as a method for improving estimation of a population mean in settings where sampling and ranking of units from the population are inexpensive when compared with actual measurement of the units. Two of the major factors in the usefulness of RSS are the set size and the relative costs of the various operations of sampling, ranking, and measurement. In this article, we consider ranking error models and cost models that enable us to assess the effect of different cost structures on the optimal set size for RSS. For reasonable cost structures, we find that the optimal RSS set sizes are generally larger than had been anticipated previously. These results will provide a useful tool for determining whether RSS is likely to lead to an improvement over simple random sampling in a given setting and, if so, what RSS set size is best to use in this case. [source] The eyes have it: visual pop-out in infants and adultsDEVELOPMENTAL SCIENCE, Issue 2 2006Scott A. Adler Visual search studies with adults have shown that stimuli that contain a unique perceptual feature pop out from dissimilar distractors and are unaffected by the number of distractors. Studies with very young infants have suggested that they too might exhibit pop-out. However, infant studies have used paradigms in which pop-out is measured in seconds or minutes, whereas in adults pop-out occurs in milliseconds. In addition, with the previous infant paradigms the effects from higher cognitive processes such as memory cannot be separated from pop-out and selective attention. Consequently, whether infants exhibit the phenomenon of pop-out and have selective attention mechanisms as found in adults is not clear. This study was an initial attempt to design a paradigm that would provide a comparable measure between infants and adults, thereby allowing a more accurate determination of the developmental course of pop-out and selective attention mechanisms. To this end, we measured 3-month-olds' and adults' saccade latencies to visual arrays that contained either a + among Ls (target-present) or all Ls (target-absent) with set sizes of 1, 3, 5 or 8 items. In Experiment 1, infants' saccade latencies remained unchanged in the target-present conditions as set size increased, whereas their saccade latencies increased linearly in the target-absent conditions as set size increased. In Experiment 2, adults' saccade latencies in the target-present and target-absent conditions showed the same pattern as the infants. The only difference between the infants and adults was that the infants' saccade latencies were slower in every condition. These results indicate that infants do exhibit pop-out on a millisecond scale, that it is unaffected by the number of distractors, and likely have similar functioning selective attention mechanisms. Moreover, the results indicate that eye movement latencies are a more comparable and accurate measure for assessing the phenomenon of pop-out and underlying attentional mechanisms in infants. [source] Effects of hippocampal lesions on the monkey's ability to learn large sets of object-place associations,HIPPOCAMPUS, Issue 4 2006Annabelle M. Belcher Abstract Earlier studies found that recognition memory for object-place associations was impaired in patients with relatively selective hippocampal damage (Vargha-Khadem et al., Science 1997; 277:376,380), but was unaffected after selective hippocampal lesions in monkeys (Malkova and Mishkin, J Neurosci 2003; 23:1956,1965). A potentially important methodological difference between the two studies is that the patients were required to remember a set of 20 object-place associations for several minutes, whereas the monkeys had to remember only two such associations at a time, and only for a few seconds. To approximate more closely the task given to the patients, we trained monkeys on several successive sets of 10 object-place pairs each, with each set requiring learning across days. Despite the increased associative memory demands, monkeys given hippocampal lesions were unimpaired relative to their unoperated controls, suggesting that differences other than set size and memory duration underlie the different outcomes in the human and animal studies. © 2005 Wiley-Liss, Inc. [source] The proportion heuristic: problem set size as a basis for performance judgmentsJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 3 2001David H. Silvera Abstract How do people evaluate their degree of mastery over a task? A series of four studies demonstrated that a potentially irrelevant cue can have a strong influence on such evaluations. In these studies, the total amount of work given to participants (the problem set size) influenced both (a) the amount of work participants completed before feeling that they had performed well and were adequately prepared for a related future task, and (b) participants' assessments of their performance and their feelings of preparedness for a related future task. These effects occurred even when a randomization procedure was used to emphasize the arbitrary nature of the problem set size. The effects vanished, however, when participants were given extra time to evaluate their progress after completing each problem. Copyright © 2001 John Wiley & Sons, Ltd. [source] Predicting the tautomeric equilibrium of acetylacetone in solution.JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2010Abstract This study investigates how the various components (method, basis set, and treatment of solvent effects) of a theoretical approach influence the relative energies between keto and enol forms of acetylacetone, which is an important model system to study the solvent effects on chemical equilibria from experiment and theory. The computations show that the most popular density functional theory (DFT) approaches, such as B3LYP overestimate the stability of the enol form with respect to the keto form by ,10 kJ mol,1, whereas the very promising SCS-MP2 approach is underestimating it. MP2 calculations indicate that in particular the basis set size is crucial. The Dunning Huzinaga double , basis (D95z(d,p)) used in previous studies overestimates the stability of the keto form considerably as does the popular split-valence plus polarization (SVP) basis. Bulk properties of the solvent included by continuum approaches strongly stabilize the keto form, but they are not sufficient to reproduce the reversal in stabilities measured by low-temperature nuclear magnetic resonance experiments in freonic solvents. Enthalpic and entropic effects further stabilize the keto form, however, the reversal is only obtained if also molecular effects are taken into account. Such molecular effects seem to influence only the energy difference between the keto and the enol forms. Trends arising due to variation in the dielectric constant of the solvent result from bulk properties of the solvent, i.e., are already nicely described by continuum approaches. As such this study delivers a deep insight into the abilities of various approaches to describe solvent effects on chemical equilibria. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Ranked Set Sampling: Cost and Optimal Set SizeBIOMETRICS, Issue 4 2002Ramzi W. Nahhas Summary. Mclntyre (1952, Australian Journal of Agricultural Research3, 385,390) introduced ranked set sampling (RSS) as a method for improving estimation of a population mean in settings where sampling and ranking of units from the population are inexpensive when compared with actual measurement of the units. Two of the major factors in the usefulness of RSS are the set size and the relative costs of the various operations of sampling, ranking, and measurement. In this article, we consider ranking error models and cost models that enable us to assess the effect of different cost structures on the optimal set size for RSS. For reasonable cost structures, we find that the optimal RSS set sizes are generally larger than had been anticipated previously. These results will provide a useful tool for determining whether RSS is likely to lead to an improvement over simple random sampling in a given setting and, if so, what RSS set size is best to use in this case. [source] Twelve- to 14-month-old infants can predict single-event probability with large set sizesDEVELOPMENTAL SCIENCE, Issue 5 2010Stephanie Denison Previous research has revealed that infants can reason correctly about single-event probabilities with small but not large set sizes (Bonatti, 2008; Teglas et al., 2007). The current study asks whether infants can make predictions regarding single-event probability with large set sizes using a novel procedure. Infants completed two trials: A preference trial to determine whether they preferred pink or black lollipops and a test trial where infants saw two jars, one containing mostly pink lollipops and another containing mostly black lollipops. The experimenter removed one occluded lollipop from each jar and placed them in two separate opaque cups. Seventy-eight percent of infants searched in the cup that contained a lollipop from the jar with a higher proportion of their preferred color object, significantly better than chance. Thus infants can reason about single-event probabilities with large set sizes in a choice paradigm, and contrary to most findings in the infant literature, the prediction task used here appears a more sensitive measure than the standard looking-time task. [source] The eyes have it: visual pop-out in infants and adultsDEVELOPMENTAL SCIENCE, Issue 2 2006Scott A. Adler Visual search studies with adults have shown that stimuli that contain a unique perceptual feature pop out from dissimilar distractors and are unaffected by the number of distractors. Studies with very young infants have suggested that they too might exhibit pop-out. However, infant studies have used paradigms in which pop-out is measured in seconds or minutes, whereas in adults pop-out occurs in milliseconds. In addition, with the previous infant paradigms the effects from higher cognitive processes such as memory cannot be separated from pop-out and selective attention. Consequently, whether infants exhibit the phenomenon of pop-out and have selective attention mechanisms as found in adults is not clear. This study was an initial attempt to design a paradigm that would provide a comparable measure between infants and adults, thereby allowing a more accurate determination of the developmental course of pop-out and selective attention mechanisms. To this end, we measured 3-month-olds' and adults' saccade latencies to visual arrays that contained either a + among Ls (target-present) or all Ls (target-absent) with set sizes of 1, 3, 5 or 8 items. In Experiment 1, infants' saccade latencies remained unchanged in the target-present conditions as set size increased, whereas their saccade latencies increased linearly in the target-absent conditions as set size increased. In Experiment 2, adults' saccade latencies in the target-present and target-absent conditions showed the same pattern as the infants. The only difference between the infants and adults was that the infants' saccade latencies were slower in every condition. These results indicate that infants do exhibit pop-out on a millisecond scale, that it is unaffected by the number of distractors, and likely have similar functioning selective attention mechanisms. Moreover, the results indicate that eye movement latencies are a more comparable and accurate measure for assessing the phenomenon of pop-out and underlying attentional mechanisms in infants. [source] Number sense in human infantsDEVELOPMENTAL SCIENCE, Issue 1 2005Fei Xu Four experiments used a preferential looking method to investigate 6-month-old infants' capacity to represent numerosity in visual-spatial displays. Building on previous findings that such infants discriminate between arrays of eight versus 16 discs, but not eight versus 12 discs (Xu & Spelke, 2000), Experiments 1 and 2 investigated whether infants' numerosity discrimination depends on the ratio of the two set sizes with even larger numerosities. Infants successfully discriminated between arrays of 16 versus 32 discs, but not 16 versus 24 discs, providing evidence that their discrimination shows the set-size ratio signature of numerosity discrimination in human adults, children and many non-human animals. Experiments 3 and 4 addressed a controversy concerning infants' ability to discriminate large numerosities (observed under conditions that control for total filled area, array size and density, item size and correlated properties such as brightness: Brannon, 2002; Xu, 2003b; Xu & Spelke, 2000) versus small numerosities (not observed under conditions that control for total contour length: Clearfield & Mix, 1999). To investigate the sources of these differing findings, Experiment 3 tested infants' large-number discrimination with controls for contour length, and Experiment 4 tested small-number discrimination with controls for total filled area. Infants successfully discriminated the large-number displays but showed no evidence of discriminating the small-number displays. These findings provide evidence that infants have robust abilities to represent large numerosities. In contrast, infants may fail to represent small numerosities in visual-spatial arrays with continuous quantity controls, consistent with the thesis that separate systems serve to represent large versus small numerosities. [source] MassSieve: Panning MS/MS peptide data for proteinsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 16 2010Douglas J. Slotta Abstract We present MassSieve, a Java-based platform for visualization and parsimony analysis of single and comparative LC-MS/MS database search engine results. The success of mass spectrometric peptide sequence assignment algorithms has led to the need for a tool to merge and evaluate the increasing data set sizes that result from LC-MS/MS-based shotgun proteomic experiments. MassSieve supports reports from multiple search engines with differing search characteristics, which can increase peptide sequence coverage and/or identify conflicting or ambiguous spectral assignments. [source] What moderates the too-much-choice effect?PSYCHOLOGY & MARKETING, Issue 3 2009Benjamin Scheibehenne Core theories in economics, psychology, and marketing suggest that decision makers benefit from having more choice. In contrast, according to the too-much-choice effect, having too many options to choose from may ultimately decrease the motivation to choose and the satisfaction with the chosen option. To reconcile these two positions, we tested whether there are specific conditions in which the too-much-choice effect is more or less likely to occur. In three studies with a total of 598 participants, we systematically investigated the moderating impact of choice set sizes, option attractiveness, and whether participants had to justify their choices. We also tested the moderating role of search behavior, domain-specific expertise, and participants' tendency to maximize, in a within-subject design. Overall, only choice justification proved to be an effective moderator, calling the extent of the too-much-choice effect into question. We provide a theoretical account for our findings and discuss possible pathways for future research. © 2009 Wiley Periodicals, Inc. [source] Ranked Set Sampling: Cost and Optimal Set SizeBIOMETRICS, Issue 4 2002Ramzi W. Nahhas Summary. Mclntyre (1952, Australian Journal of Agricultural Research3, 385,390) introduced ranked set sampling (RSS) as a method for improving estimation of a population mean in settings where sampling and ranking of units from the population are inexpensive when compared with actual measurement of the units. Two of the major factors in the usefulness of RSS are the set size and the relative costs of the various operations of sampling, ranking, and measurement. In this article, we consider ranking error models and cost models that enable us to assess the effect of different cost structures on the optimal set size for RSS. For reasonable cost structures, we find that the optimal RSS set sizes are generally larger than had been anticipated previously. These results will provide a useful tool for determining whether RSS is likely to lead to an improvement over simple random sampling in a given setting and, if so, what RSS set size is best to use in this case. [source] | |||||||||||||