Membership Decision Research Articles

An Insight Review on Bloom Filter and Its Variants with Applications: An Emerging Hash Based Membership Querying Technique

Bloom filter idea was bloomed in the early seventy's as an efficient data structure tool for intelligent dictionary and spell check purposes and later revisited by the research community for its dynamic membership decision making and querying ability. Recently various optimization models for diverse applications emerged. Bloom filters are now implied in various networking applications, security applications and other emerging areas which require intensive querying and compact storage. Still it has scope for optimization and utilization. In this paper we present an insight survey on bloom filter and its variants and also discuss the applications and issues. This review will highly benefit the research community working in this field.

Economic Analysis of the Role of Farmer Organizations in Enhancing Smallholder Potato Farmers’ Income in Middle Guinea

Farmers’ organizations are inclusive of the poor and are charged with the purpose of becoming a market outlet for smallholder farmers in Guinea. Improving farmers’ income earning capability and agricultural productivity has been an important strategy of Guinea’s agriculture development policy. However, despite their growing importance, empirical studies on how farmers’ organizations have impacted their members’ income are limited in Guinea. This paper investigates the determinants and effects on farm income of group membership, using the sample of 90 smallholder potato producers in Middle Guinea. A probit model was used as a selection equation to identify factors that influence group membership decision by smallholder potato farmers. The results revealed that the age of the potato farmers, land ownership, extension service, credit access and off-farm income are positively associated with group membership while gender and education level of the farmer negatively influenced their decision to join farmer groups. Results of the second stage outcome equation found positive farm income effects of group membership. Furthermore, results revealed that farm income is predominantly determined by labor used, the size of the cultivated potato area, share of potato sold and potato market price. Since farmers are resource-poor and that farmer organizations are constrained by various institutional, technical and investment constraints despite their potential, it is recommended that favorable polices should be geared toward smallholder agriculture in Guinea in order to ensure the success of farmer organizations. Our results show that farmer groups can be an important institution for the transformation of smallholder farming, increase productivity and incomes thereby reducing poverty. Agricultural policies in Guinea should therefore focus more on the intensification of agriculture and farmers’ organizations and increase the market orientation of the smallholder farm sector.

Applications of Algebra for Some Game Theoretic Problems

In this paper we present applications of polynomial algebra for the problem of computing Nash equilibria of a subclass of finite normal form games.We characterize Nash equilibria of a normal form game as solutions to a system of polynomial equations and define the subclass of games under consideration. We present an algebraic method for deciding membership decision to the subclass of games. A method based on group action to compute all Nash equilibria of the subclass of games is presented with examples to show working of the methods. We also present some related results and discuss properties of the subclass of games.

Unsupervised classification of polarimetric synthetic aperture radar images using kernel fuzzy C-means clustering

In this article, an unsupervised clustering approach, known as the kernel fuzzy C-means (KFCM), which is based on Cloude's decomposition, is used for polarimetric synthetic aperture radar (POLSAR) image classification. The KFCM algorithm is an improved version of the fuzzy C-means (FCM) algorithm. It replaces the original Euclidean distance measure by the kernel-induced distance. The original sample space, coherency matrix T, is mapped to a higher-dimensional feature space so as to simplify the complex POLSAR data by using the Gaussian kernel function. The method has three main steps: first, the eight initial centres are obtained by averaging the coherency matrix within each partition according to the classical H/α plane so as to preserve the polarimetric property reasonably well; second, the related parameters of the KFCM algorithm are iteratively refined and third, the membership matrix is defuzzified by using the maximum membership decision rule. The distance measure used in the algorithm is derived from the complex Wishart distribution of the pixel data presented in the coherence data. The KFCM method not only takes advantage of the polarimetric scattering properties but also utilises the kernel method to cluster the nonlinear structure data with noise. The feasibility of this approach was tested by using two JPL/AIRSAR polarimetric SAR images. The experimental results showed that the KFCM clustering algorithm was better than the FCM clustering algorithm at classifying the POLSAR images.

The effect of church tax on church membership

In this study, we examine the effect of church tax on the church membership decision using Finnish data. We present both descriptive statistics from an opting-out website and econometric evidence exploiting the panel structure of a large individual-level data set. Our descriptive analysis shows that opting out is concentrated towards the last days of the year, i.e., the last chance to avoid paying church tax for the entire coming year. Our econometric evidence suggests that the average effect of tax incentives for the whole population is both statistically and economically significant. A 1 standard deviation increase in church tax leads to between 0.5 and 1 percentage point decline in the likelihood of church membership. In addition, we find that church membership dropped substantially when a law change made opting out significantly easier. This finding suggests that transaction costs play an important role in the membership decision.

The Effect of Church Tax on Church Membership

In this study we examine the effect of church tax on the church membership decision using Finnish data. We present both descriptive statistics from an opting-out website and econometric evidence exploiting the panel structure of a large individual-level data set. Our descriptive analysis shows that opting-out is concentrated towards the last days of the year, i.e., the last chance to avoid paying church tax for the entire coming year. Our econometric evidence suggests however, that the average effect of tax incentives in the whole population is very small in magnitude, while being statistically significant. The price elasticity of church membership is roughly -0.01. In addition, we find that church membership dropped substantially when a law change made opting-out significantly easier. This finding suggests that transaction costs play an important role in the membership decision.

A NAIVE BAYES SOURCE CLASSIFIER FOR X-RAY SOURCES

ABSTRACT The Chandra Carina Complex Project (CCCP) provides a sensitive X-ray survey of a nearby starburst region over >1 deg2 in extent. Thousands of faint X-ray sources are found, many concentrated into rich young stellar clusters. However, significant contamination from unrelated Galactic and extragalactic sources is present in the X-ray catalog. We describe the use of a naive Bayes classifier to assign membership probabilities to individual sources, based on source location, X-ray properties, and visual/infrared properties. For the particular membership decision rule adopted, 75% of CCCP sources are classified as members, 11% are classified as contaminants, and 14% remain unclassified. The resulting sample of stars likely to be Carina members is used in several other studies, which appear in this special issue devoted to the CCCP.

Why did Farmers Belong to Interest Groups? Evidence on the Causes of Membership from the Farmers' Alliance

Although Mancur Olson’s model of selective incentives (1965) is a cornerstone of public choice theory, the model has not been carefully tested. Researchers have lacked representative data on interest group members and nonmembers or information about the economic benefit of membership. This paper tests Olson’s model using data on the Farmers’ Alliance, a large and influential interest group in the late 1800s. Olson’s model does not explain well the causes of membership in the Alliance. Analysis of wealth accumulation shows there was not an economic benefit of membership for the typical member and the economic benefit of membership did not influence the decision to join. Instead, the expected benefit of Alliance lobbying, a collective good, had the largest impact on the membership decision. These findings suggest the barriers to collective action in large interest groups are not as high as Olson supposed and help to explain the political power of farmers in U.S history.

Verbal Repetition in the Reappraisal of Contamination-Related Thoughts

Acceptance and Commitment Therapy advocates use of cognitive defusion techniques to reduce the distress evoked by negative thoughts, including verbal repetition (VR). In VR, a negative word is repeated until its semantic meaning is diluted (i.e. until semantic satiation is achieved). The present two studies examined whether VR is more effective than brief imaginal exposure (IE) and no intervention (CONT) in the reappraisal of contamination-related thoughts. Participants high in contamination fears identified their most distressing thoughts and were randomly assigned to VR, IE, or CONT. A category membership decision task was also conducted to determine if VR produced semantic satiation. In Study 1, there was no evidence of semantic satiation. Significant reductions in negative response to the thoughts was observed immediately following VR, but not IE or CONT; however, at one-week follow-up, both VR and IE groups reported similar reductions. In Study 2, the effects of VR and IE practice between post-intervention and follow-up were examined, as well as changes in behavioural avoidance. VR was found to produce semantic satiation of contamination thoughts, and VR was associated with less negative response at follow-up relative to IE and CONT, but the degree of satiation was not associated with the decreases in negative response. Only IE produced decreases in behavioural avoidance and vigilance monitoring. Taken together, these results suggest that VR may have potential as an additional strategy for managing obsessional thoughts, but more research is warranted.

Time-related processes in time-based prospective memory and in time-interval production

Time-based prospective memory tasks require the retrieval of previously formed plans (e.g., call me on my mobile phone) either at a specified time (e.g., at 3 p.m.) or after a specified period of time has elapsed (e.g., in 3 min). In the present study, we investigated whether the same time-related processes are recruited for a short-duration time-based prospective memory task and for a time-interval production task. In a dual-task paradigm, we required young adult participants to make category-membership decisions, while they were simultaneously engaged either in a time-based prospective memory tasks or in a time-interval production task. Under one set of conditions, participants were instructed to allocate attention equally to the two tasks, whereas in another set of conditions, they allocated attention primarily to the time-relevant task. The findings revealed that time estimates were not affected by the attention allocation manipulation, although it influenced performance on the concurrent category membership decision making task, and as expected time estimates were more accurate on the prospective memory task than on the time-production task. Based on the preponderance of the findings, we suggest that timing is managed by different mechanisms and/or strategies on time-interval production tasks and on short-duration time-based prospective memory tasks.

Differences in Decline: Quantile Regression Analysis of Union Wage Differentials in the United Kingdom, 1991-2003

Wage premia related to union membership and coverage are examined over 1991-2003, a period involving first decline, then stabilization, of unionization. Differences in union premia across workers and over time are studied using individual-level British Household Panel Survey data and quantile regression techniques allowing for endogeneity of the membership decision. Raw differentials suggest the presence of large positive membership and coverage premia that are stronger at the bottom of the wage distribution in both private and public sectors. After controlling for other factors influencing wages, union asymmetries are no longer apparent in the private sector. When endogeneity of union membership is taken into account, the private sector union wage premium disappears, indicating that individuals positively select into unions. In contrast, the public sector total union wage premium remains significant – entirely due to a coverage effect; it is stronger at the bottom among males, while for females the premium is constant across workers and substantial over the whole period, reflecting the continuing strength of public sector unions. Once we control for endogeneity, the membership premium is nowhere significant; there is no free rider puzzle in the private sector, as there is no coverage premium, but the puzzle persists for the public sector.

Do loyalty programs really enhance behavioral loyalty? An empirical analysis accounting for self-selecting members

One of the pressing issues in marketing is whether loyalty programs really enhance behavioral loyalty. Loyalty program members may have a much higher share-of-wallet at the firm with the loyalty program than non-members have, but this does not necessarily imply that loyalty programs are effective. Loyal customers may select themselves to become members in order to benefit from the program. Since this implies that program membership is endogenous, we estimate models for both the membership decision (using instrumental variables) and for the effect of membership on share-of-wallet, our measure of behavioral loyalty. We use panel data from a representative sample of Dutch households who report their loyalty program memberships for all seven loyalty programs in grocery retailing as well as their expenditures at each of the 20 major supermarket chains. We find a small positive yet significant effect of loyalty program membership on share-of-wallet. This effect is seven times smaller than is suggested by a naïve model that ignores the endogeneity of program membership. The predictive validity of the proposed model is much better than for the naïve model. Our results show that creating loyalty program membership is a crucial step to enhance share-of-wallet, and we provide guidelines on how to achieve this.

Does Union Membership Really Reduce Job Satisfaction?

AbstractWe investigate the effect of union membership on job satisfaction. Using linked employer–employee data from the 1998 British Workplace Employee Relations Survey, we analyse the relationship between the membership decision and overall job satisfaction and satisfaction with pay. In this paper we account for the endogenous selection induced by the sorting of workers into unionized jobs. Controlling for both individual and establishment heterogeneity and explicitly modelling the effect of union status, we find that the marked difference in job satisfaction between unionized and non‐unionized workers disappears, suggesting that a selection effect, rather than a causal effect, characterizes the relationship.

Hemispheric effects of canonical views of category members with known typicality levels

Is there a preferred hemispheric canonical view of a concept? We investigated this question in a natural superordinate category membership decision task using a hemifield paradigm. Participants had to decide whether or not an image of an object lateralized in the left (LVF) or right (RVF) visual half-field is a member of a predesignated superordinate category. The objects represented high, medium, or low typicality levels, and each object had six different perspective views (front, front-right, front-left, side, back-left, and back-right). The latency responses revealed a significant interaction of Hemi Field X View X Typicality (there wasno hemifield difference in accuracy). The findings confirm the presence of asymmetry in stored concepts in long-term memory and suggest, in addition, a hemispheric canonical view of these concepts, a view strongly related to typicality level.

Word Priming without Awareness: A New Approach to Circumvent Explicit Memory Contamination

A major methodological limitation arising in the experimental study of implicit memory is that tasks that are characterized as implicit memory tests can be seriously contaminated by the use of covert explicit memory strategies. Given the evidence indicating that brief presentation of words (below the awareness threshold of subjects) can produce semantic priming, we wondered whether rapid visual presentation of primed words might provide an avenue to produce word priming without explicit memory contamination. Normal subjects were tested for word priming on a speeded category membership decision task. Explicit or implicit encoding procedures were used in four different experiments. Results demonstrated that brief presentation of words can indeed offer a means of producing word priming in absence of explicit recognition or recall of the primed words presented during the study phase. They also showed that such priming is equivalent in degree to the priming measured when using either a conventional implicit memory design or an explicit encoding procedure prior to the study of the primes.

Jurassic Union Man? A Profile of the British Trade Union Member

This paper examines the determinants of trade union membership in Great Britain utilising micro‐data taken from the British Social Attitudes Survey over the period 1985–91. Our results suggest that, contrary to previous micro‐studies, personal characteristics and the perceptions of workers' attitudes as regards their working environment impact significantly upon the decision to join a trade union. Moreover, it would appear that the union membership decision is becoming increasingly endogenised, especially in the case of the white‐collar worker.

On the solidarity of the union membership decision in Poland

It is frequently held that the old “official” unions have largely been discredited, while numerous studies point to employee dissatis‐faction with the performance of unions new and old in the era of transformation in Central and Eastern Europe. Nevertheless, membership has not collapsed, although the unions themselves exaggerate its total. It is somewhat surprising therefore that little work has been undertaken on the determinants of the individual union‐joining decision in the new environment. This paper undertakes such a study for the case of Poland. Notwithstanding reputation effects, two further forces have accompanied the collapse of the communist regime and are likely to have reduced the attractiveness of union membership to workers. The first is the widespread loss of the distributive role with regard to important private goods which the unions previously possessed, while the second is the challenge to the strength of the social custom of union membership which systemic change has occasioned. While the transition economies are often held to have a distinct industrial relations system, in Poland at least, the determinants of the individual union‐joining decision appear very similar to those which have been uncovered in western contexts.

Context effects in a category verification task as assessed by event-related brain potential (ERP) measures

This study examined the extent to which decisions about category membership (between category structure) are dependent on or dissociable from the typicality structure (within category structure) of categories. To this end, behavioral and event-related brain potential (ERP) measurements were obtained in a category verification task that incorporated a context manipulation (list composition effect) that was previously shown to affect membership verification. In a German and an American English version of the experiment, pairs of words were presented and subjects were asked to decide whether or not the second word was an exemplar of the superordinate indicated by the first word. Both versions yielded similar results. The behavioral data showed that both typicality and context manipulation affected the verification times for the true exemplars. Furthermore, atypical true exemplars were affected more by context manipulation than mere typical ones. By contrast, the N400 component of the ERPs elicited by the true exemplars was influenced by typicality, but invariant in the face of the context manipulation. These results underscore the previously shown dissociation between reaction times and N400 changes and suggest that category membership decision (as reflected in verification times) and semantic relatedness or typicality of an exemplar (as reflected in N400 modulation) can vary independently from each other and, therefore, likely index the activity of different brain systems.

Word Priming During and After Transient Global Amnesia: A Case Report

Abstract Many studies have shown relative preservation of word priming in subjects with mild amnesia, but some impairment in severe amnesia. This calls into question the degree of separation between implicit and explicit memory. Possible contamination of implicit memory tasks by impaired explicit memory strategies might be obscuring the actual dissociation between the two memory systems. We have developed a method of circumventing explicit memory contamination by using brief duration repeated primes below the awareness threshold of subjects. We have used this approach to evaluate the status of word priming in a 70-year-old woman with transient global amnesia. This subject was examined during her attack as well as 8 months after. She was tested for word priming on a speeded category membership decision task. Implicit or explicit encoding procedures were used in three different experiments. Results indicated that there was no significant difference between the priming effects measured in the implicit and explicit conditions or between the priming effects measured during and after the transient global amnesia attack. Results also confirmed that brief multiple presentation of words can offer a means of producing word priming in the absence of explicit recognition or recall of the primed words in amnesia. These findings demonstrate that word priming is preserved during transient global amnesia. They also suggest that the capacity to encode, store and retrieve information implicitly, e.g. unintentionally, is retained in this neurological condition.

Word priming during and after transient global amnesia: A case report

Many studies have shown relative preservation of word priming in subjects with mild amnesia, but some impairment in severe amnesia. This calls into question the degree of separation between implicit and explicit memory. Possible contamination of implicit memory tasks by impaired explicit memory strategies might be obscuring the actual dissociation between the two memory systems. We have developed a method of circumventing explicit memory contamination by using brief duration repeated primes below the awareness threshold of subjects. We have used this approach to evaluate the status of word priming in a 70-year-old woman with transient global amnesia. This subject was examined during her attack as well as 8 months after. She was tested for word priming on a speeded category membership decision task. Implicit or explicit encoding procedures were used in three different experiments. Results indicated that there was no significant difference between the priming effects measured in the implicit and explicit conditions or between the priming effects measured during and after the transient global amnesia attack. Results also confirmed that brief multiple presentation of words can offer a means of producing word priming in the absence of explicit recognition or recall of the primed words in amnesia. These findings demonstrate that word priming is preserved during transient global amnesia. They also suggest that the capacity to encode, store and retrieve information implicitly, e.g. unintentionally, is retained in this neurological condition.