Measure Of Associative Strength Research Articles

4-OR: Diabetes Duration and the Relative Importance of Cardiovascular Risk Factors in Type 1 Diabetes

Based on a Diabetes Control and Complications Trial (DCCT)/Epidemiology of Diabetes Interventions and Complications (EDIC) report and their own findings, Pittsburgh Epidemiology of Diabetes Complications investigators concluded that the relative impact of HbA1c and kidney disease in type 1 diabetes (T1D) on cardiovascular disease (CVD) varies according to T1D duration. We investigate the relative importance of HbA1c and other CVD risk factors during ∼ 30 years of DCCT/EDIC follow-up within the primary (RET-: subjects with a mean T1D duration of 2.6 years and without retinopathy at baseline) and within the secondary DCCT cohort (RET+: subjects with a mean T1D duration of 8.6 years and with mild to moderate retinopathy at baseline). CVD included fatal/nonfatal myocardial infarction (MI) or stroke, silent MI, revascularization, confirmed angina, or congestive heart failure. Cox regression models with robust error variances were used to find the most significant CVD risk factors (p<0.05) within RET- and within RET+. The importance of risk factors was determined by evaluating the z value, a measure of association strength between risk factor and CVD. In case of hazard assumption violation, time by covariate interaction was included in model. DCCT enrolled 1441 subjects (age 13-39); 115 of 715 RET+ subjects and 69 of 726 RET- subjects had a CVD event. For RET+, the most important risk factors were baseline (B) age (z ∼4.2), time dependent (T) mean (M) systolic blood pressure (SBP) (z ∼4.0), any severe hypoglycemia (z ∼3.7), and TM HbA1c (z ∼3.2). Other significant risk factors included B autonomic neuropathy, TM insulin dose, TM LDL, T current (C) ACE inhibitor use, TC insulin regimen and B severity of retinopathy but not T1D duration. For RET-, B age, TM HbA1c, TC triglycerides and TM SBP with an increasing CVD effect over follow-up time were significant. The relative importance of CVD risk factors in a young T1D cohort varies according to microvascular complications, which correlate with T1D duration. Disclosure E.R. Fahrmann: None. H. Driscoll: None.

If You Don't Have Valence, Ask Your Neighbor: Evaluation of Neutral Words as a Function of Affective Semantic Associates.

How do humans perform difficult forced-choice evaluations, e.g., of words that have been previously rated as being neutral? Here we tested the hypothesis that in this case, the valence of semantic associates is of significant influence. From corpus based co-occurrence statistics as a measure of association strength we computed individual neighborhoods for single neutral words comprised of the 10 words with the largest association strength. We then selected neutral words according to the valence of the associated words included in the neighborhoods, which were either mostly positive, mostly negative, mostly neutral or mixed positive and negative, and tested them using a valence decision task (VDT). The data showed that the valence of semantic neighbors can predict valence judgments to neutral words. However, all but the positive neighborhood items revealed a high tendency to elicit negative responses. For the positive and negative neighborhood categories responses congruent with the neighborhood's valence were faster than incongruent responses. We interpret this effect as a semantic network process that supports the evaluation of neutral words by assessing the valence of the associative semantic neighborhood. In this perspective, valence is considered a semantic super-feature, at least partially represented in associative activation patterns of semantic networks.

Contribution of Genome–Environment Interaction to Pre-eclampsia in a Havana Maternity Hospital

Pre-eclampsia is a major cause of morbidity and mortality during pregnancy worldwide and is among the leading causes of maternal mortality in Cuba. It is a complex, multifactoral disease, in which interaction of genetic and environmental factors should not be overlooked if the goal is proper risk assessment to sup- port personalized preventive genetic counseling and more effective prenatal care to prevent pregnancy complications. OBJECTIVE Determine the contribution to pre-eclampsia of interac- tion between a predisposing genome and adverse environmental fac- tors in pregnant women in a Havana maternity hospital. METHODS This was the exploratory phase of a hospital-based case-control study, using January 2007-December 2009 patient records from the Eusebio Hernandez University Hospital, a prov- incial maternity hospital in Havana. Eighty pregnant women diag- nosed with pre-eclampsia and 160 controls were studied. The main variables were age, parity, nutritional status (measured by BMI), alcohol use, tobacco use, and history of pre-eclampsia in relatives of the pregnant woman (proband) or of her partner. Pearson chi square and Fisher exact test were used to assess statistical signifi cance of associations between variables and odds ratio as a measure of association strength. Familial aggregation was studied and a case- control design used to assess gene-environment interaction, using multiplicative and additive models.

Effect Sizes and F Ratios < 1.0

Abstract. Standard statistics texts indicate that the expected value of the F ratio is 1.0 (more precisely: N/(N-2)) in a completely balanced fixed-effects ANOVA, when the null hypothesis is true. Even though some authors suggest that the null hypothesis is rarely true in practice (e.g., Meehl, 1990 ), F ratios < 1.0 are reported quite frequently in the literature. However, standard effect size statistics (e.g., Cohen's f) often yield positive values when F < 1.0, which appears to create confusion about the meaningfulness of effect size statistics when the null hypothesis may be true. Given the repeated emphasis on reporting effect sizes, it is shown that in the face of F < 1.0 it is misleading to only report sample effect size estimates as often recommended. Causes of F ratios < 1.0 are reviewed, illustrated by a short simulation study. The calculation and interpretation of corrected and uncorrected effect size statistics under these conditions are discussed. Computing adjusted measures of association strength and incorporating effect size confidence intervals are helpful in an effort to reduce confusion surrounding results when sample sizes are small. Detailed recommendations are directed to authors, journal editors, and reviewers.

Seasonal Changes in Male Associative Behavior and Subgrouping of Alouatta palliata on an Island

Howler groups are usually spatially cohesive and stable in composition; however, more flexible grouping patterns occur in some social groups. We analyzed the associative and subgrouping patterns of males living in a group with fission-fusion social organization. Based on information from previous studies on Alouatta palliata and other primates and in the current socioecological models, we established initial predictions on the variations in male behavior according to several socioecological factors. We studied associative behavior via scan sampling at 15-min intervals to register the identity of males in the subgroups and the presence and number of receptive females. We calculated an association index that was then transformed into a measure of association strength. We found individual association trends, as well as important seasonal differences in the subgrouping patterns of males. During the dry season the presence of many receptive females resulted in reduced levels of association, and therefore fewer males per subgroup. The scenario changed during the wet season, when males grouped together significantly more and kinship relationships were a major determinant for individual association preferences.

T-value and mutual information as measures of the association strength in Serbian language

Since the study of Meyer and Schvaneveldt (1971), a large number of researches have shown facilitation effect in cognitive processing of a given word when it is preceded by a semantically (i.e. associatively) related word. In this study, we examined influence of association strength between context and target on visual word processing in Serbian language. Primary goal was to test cognitive relevance of the t-value and mutual information (MI) as measures of the association strength. The results showed that the mutual information affects response latencies in the visual lexical decision task: the higher the mutual information for two words (bigram), the shorter the reaction time. Contrariwise, cognitive relevance of the t-value as a measure of the words' association strength was not confirmed.

Direct Estimation of Correlation as a Measure of Association Strength Using Multidimensional Item Response Models

The Pearson correlation is used to depict effect sizes in the context of item response theory. Amultidimensional Rasch model is used to directly estimate the correlation between latent traits. Monte Carlo simulations were conducted to investigate whether the population correlation could be accurately estimated and whether the bootstrap method provided a good approximation of the distribution of the sample correlation. The independent variables were (a) the item response model, (b) test length, (c) sample size, and (d) the magnitude of correlation. The dependent variable was the empirical correlation coefficient. The results indicate that the population correlation can be accurately estimated and that the bootstrap method yields very a good approximation of the sampling distribution.

What some effects might not be: the time to verify membership in "well-defined" categories.

Armstrong, Gleitman, and Gleitman (1983) reported shorter categorization times for members of well-defined categories judged more typical. They concluded that these effects could not originate in a graded, similarity-based category representation and consequently that the typicality effects obtained with natural categories might not be indicative of such a structure either. In this article, we re-examine this conclusion, focusing first on the performance obtained with well-defined categories of different sizes. Only the larger categories used showed variations in typicality ratings and produced typicality effects on categorization times. However, multiple regression analyses showed the effects on categorization times to be better explained by a measure of associative strength, called category dominance. The range of various predictor variables was equated in a follow-up experiment involving large, natural, and well-defined categories. Results obtained with well-defined categories showed pronounced dominance effects when typicality was controlled, but no reliable typicality effect when category dominance and instance familiarity were controlled. Results were opposite for natural categories. By showing that well-defined categories fail to produce unbiased typicality effects, our results bring added support to the hypothesis that the effects obtained with natural categories originate in a graded, similarity-based category structure.

Calorimetric investigation of guanidinium-carboxylate interactions

Isothermal titration calorimetry was utilized to study the association between a series of guanidinium derivatives and tetrabutylammonium acetate. This technique provides a measure of association strength, stoichiometry of binding, as well as thermodynamic parameters of association from a single experiment. Guanidinium derivatives which can form bidentate linear hydrogen bonds with acetate show significant, exothermic binding in DMSO (Ka = 5600 M −1; ΔH = −3.6 kcal/mol), while derivatives which lack this bidentate linear hydrogen bonding interaction result in complexes where association is weaker (Ka ≈ 100 M −1) and enthalpically neutral or endothermic. Additionally calorimetry permits the complete assessment of the multiple binding equilibria when derivatives complex two equivalents of guest.

Conditional Probability May be a Flawed Measure of Associative Strength

The failure to adjust for chance may make conditional probability an imperfect measure of associative strength. We argue that this flaw may limit theoretical interpretations of the patterns of conditional probabilities obtained in previous research. This is demonstrated through comparisons of obtained and expected conditional probabilities using both hypothetical and actual data. Two alternative measures are suggested to adjust for this flaw: a conditional probability difference score (CPDIFF) and the Adjusted Ratio for Individual Sequences (ARIS).

Blocking with a single compound trial

Three theories of classical conditioning were examined with regard to the earliest conditioning trial on which blocking could first occur. One theory (Rescorla & Wagner, 1972) predicts the occurrence of blocking on the first compound trial, whereas the other two (Mackintosh, 1975b; Pearce & Hall, 1980) predict that blocking will not occur until after the first compound trial. Using conditioned suppression of licking in water-deprived rats as a measure of associative strength, we found that substantial blocking of tone-footshock (X-US) associations occurred when a single light plus tone-footshock (AX-US) pairing followed 12 A-US pairings. The results are discussed in light of previous attempts to obtain one-trial blocking, and the implications of all of these studies for classical conditioning theory are considered.

Reminder-induced recovery of associations to an overshadowed stimulus

The possibility of reversing the deficit produced by overshadowing through the use of memory reactivation was investigated. Using lick suppression as a measure of associative strength, water-deprived rats were conditioned in a Pavlovian paradigm which produced reliable overshadowing of a flashing light by a tone. It was found, however, that exposure to the overshadowed stimulus outside of the conditioning context during the retention interval (reminder treatment) caused an increase in lick suppression during testing in animals that had undergone overshadowing, relative to nonreminded overshadowed animals. Subjects that received the reminder treatment but were conditioned without overshadowing showed no increase in lick suppression. Additional control groups ensured that the increase in suppression observed in the overshadowed subjects following reminder treatment was not due to nonspecific fear. The results suggest that the performance deficit produced by overshadowing is due at least in part to a reversible failure to efficiently retrieve associations to the overshadowed stimulus at the time of testing, rather than a failure to form those associations during conditioning.

Associative frequency as a measure of associative strength

FlekkØy, K. Associative frequency as a measure of associative strength. Scand. J. Psychol., 1973, 14, 99–102. ‐Associative frequency in a group of subjects has been assumed to reflect associative strength in the individual. This hypothesis was tested by comparing frequency rank of responses in a single‐word free‐association situation with sequence of emission of the same responses in a continued situation. The results indicate that associative frequency reflects associative strength, but not to an extent which will allow the identification of individual associative‐strength hierarchies.

Response latencies in short-term memory.

This paper deals with the problem of the interpretation of response latencies in short-term memory. A paired-associate study using a probe technique was conducted with the main experimental variation the length of the recall interval (1, 2, or 4 sec.). While shortening the interval had a statistically significant effect on recall probability the interaction between recall interval and probe position was negligible. While traditionally response latency is considered a measure of associative strength, such an interpretation seems inappropriate here. As an alternative, latencies may reflect more criterion values than sensitivity as these measures are interpreted in signal-detection theory.

RELATION BETWEEN SINGLE WORD ASSOCIATION AND CONTINUED ASSOCIATION RESPONSE HIERARCHIES.

Association data for 20 words were obtained through two methods, single word association and continued association. Response frequencies in single word association were correlated with response frequencies in continued association and with a measure of association strength in continued association which took into account frequency and average order of emission of response words. The latter correlations ranged from .52 to .94 and were in each case higher than the corresponding frequency-frequency correlations. It was concluded that continued association and single word association produce similar response hierarchies and that order of emission is related to association strength in continued association. It was suggested that the order of emission-frequency measure developed in this paper may be an economical and perhaps useful measure of association strength.