Strong Causal Relationship Research Articles

The Relationship between Self-Concept and Performance in Grade 11 Mathematics

This paper reports on a study aimed at answering the question whether there is any difference between high and low performers among some grade 11 mathematics learners in Mangaung high schools. The study looks at differences in terms of how they understand their mathematics performance and make sense of themselves (abilities, capabilities, etc.). No strong causal relationship is assumed but the results tend to show that performance is positively related to self-concept. The higher the level of positive self-regard, the higher is also the level of performance, at the same time. The inverse also applies. This conclusion was arrived at after analysing and interpreting quantitative findings using Mboya's Self-Description Inventory-II (MSDI-II), Tuckman's Mathematics Attitude Scale (MAS) and Rotter's Internal-External Scale.

Analysis of Metropolitan Highway Capacity and the growth in vehicle miles of travel

A number of recent studies have examined the hypothesis of induced travel in an attempt to quantify the phenomenon (Hansen & Huang 1997; Noland, forthcoming). No study has yet attempted to adjust for potential simultaneity bias in the results. This study addresses this issue by the use of an instrumental variable (two stage least squares) approach. Metropolitan level data compiled by the Texas Transportation Institute for their annual congestion report is used in the analysis and urbanized land area is used as an instrument for lane miles of capacity. While this is not an ideal instrument, results still suggest a strong causal relationship but probably that most previous work has had an upward bias in the coefficient estimates. The effect of lane mile additions on VMT growth is forecast and found to account for about 15% of annual VMT growth with substantial variation between metropolitan areas. This effect appears to be closely correlated with percent growth in lane miles, suggesting that rapidly growing areas can attribute a greater share of their VMT growth to growth in lane miles.

Long‐term phytoplankton‐nutrient interactions in a shallow coastal sea: Algalcommunity structure, nutrient budgets, and denitrification potential

In the eutrophic Marsdiep, the westernmost tidal inlet of the Wadden Sea, phytoplankton biomass, and production almost doubled at the end of the 1970s and remained high ever since. Principal component analysis of 21‐yr (1974–1994) high‐resolution time series of the 32 most numerous marine algal species revealed that the phytoplankton community changed drastically both between 1976 and 1978 and again between 1987 and 1988, and that it was relatively stable in‐between (1974–1976, 1978–1987) and thereafter (1988–1994). These major changes in phytoplankton biomass and species composition coincided with changes in absolute and relative (TN:TP) nutrient concentrations. During the summer of 1977, the Marsdiep shifted from a rich, but phosphorus‐controlled system to an even more eutrophic but nitrogen‐controlled environment. The system reshifted towards P‐control between 1987 and 1988. The coincidence of the shifts in relative nutrient concentrations and phytoplankton species composition implies a strong causal relationship between TN:TP ratios and phytoplankton community structure. Among diatoms, the observed increase in phytoplankton biomass under eutrophic N‐controlled conditions was particularly due to an increase of the abundance of larger algae. Our results indicate that the N budget of the area is correlated with the community structure, suggesting enhanced loss of nitrogen to the sediment through increased deposition of larger algal cells.

Phonological Awareness and Reading: An Alternative Interpretation of the Literature from a Clinical Perspective

Many researchers have concluded that there is a strong causal relationship between phonological awareness and reading, and that deficiency in phonological awareness is a major factor in reading problems. This article provides an alternative interpretation based on a critical analysis of the research literature and three clinical case studies. On the basis of our results, we hypothesize that rather than phonemic awareness per se, what seems to be essential to learning to read is that children develop an understanding of the connections between oral and written language. At the macrolevel this involves an understanding that written words represent words in oral language. At the microlevel it involves understanding that letters in written words stand for phonemes in spoken words.

Testing for linear and nonlinear granger causality in the stock price-volume relation: Korean evidence

In this paper, linear and nonlinear Granger causality tests are used to examine the dynamic relationship between daily Korean stock returns and trading volume. We find evidence of significant bidirectional linear and nonlinear causality between these two series. ARCH-ype models are used to examine whether the nonlinear causal relations can be explained by stock returns and volume serving as proxies for information flow in the stochastic process generating volume and stock returns respectively. After controlling for volatility persistent in both series and filtering for linear dependence, we find evidence of nonlinear bidirectional causality between stock returns and volume series. The finding of strong bidirectional stock price-volume causal relationships implies that knowledge of current trading volume improves the ability to forecast stock prices. This evidence is not supportive of the efficient market hypothesis. Another finding is that the nonlinear relationship is sensitive to institutional, organizational, and structural factors. The results of this study should be useful to regulators, practitioners and derivative market participants whose success precariously depends on the ability to forecast stock price movements.

Maternal education and child health: Is there a strong causal relationship?

Using data from the first round of Demographic and Health Surveys for 22 developing countries, we examine the effect of maternal education on three markers of child health: infant mortality, children's height-for-age, and immunization status. In contrast to other studies, we argue that although there is a strong correlation between maternal education and markers of child health, a causal relationship is far from established. Education acts as a proxy for the socioeconomic status of the family and geographic area of residence. Introducing controls for husband's education and access to piped water and toilet attenuate the impact of maternal education on infant mortality and children's height-for-age. This effect is further reduced by controlling for area of residence through the use of fixed-effects models. In the final model, maternal education has a statistically significant impact on infant mortality and height-for-age in only a handful of countries. In contrast, maternal education remains statistically significant for children's immunization status in about one-half of the countries even after individual-level and community-level controls are introduced.

Breaking Trends and the Money-Output Correlation

This paper examines the impact on the money-output correla-tion of a univariate specification that allows time series to be characterized as stationary around a broken trend function. Though pretesting suggests that U.S. real output (industrial production) can be described as broken-trend stationary, this result has only limited impact on the money-output correlation. Before 1985 there is a strong Granger causal relationship between money and broken-detrended output (but not first-differenced output), even when different short-term interest rates are used as regres-sors. However, after 1985 this relationship weakens significantly, whether or not one determines that output has a unit root.

Intrauterine Growth Retardation in Iowa Communities with Herbicide-Contaminated Drinking Water Supplies

In a statewide survey of 856 Iowa municipal drinking water supplies in 1986-1987 the Rathbun rural water system was found to contain elevated levels of triazine herbicides. Rates of low birth weight, prematurity, and intrauterine growth retardation (IUGR) in live singleton births during the period 1984-1990 by women living in 13 communities served by the Rathbun water system were compared to other communities of similar size in the same Iowa counties. The Rathbun communities had a greater risk of IUGR than southern Iowa communities with other surface sources of drinking water (relative risk = 1.8; 95% CI = 1.3, 2.7). Multiple linear regression analyses revealed that levels of the herbicides atrazine, metolachlor, and cyanzinc were each significant predictors of community IUGR rates in southern Iowa after controlling for several potentially confounding factors including maternal smoking and socioeconomic variables. The association with IUGR was strongest for atrazine, but all three herbicides were intercorrelated and the independent contributions of each to IUGR risk could not be determined. We conclude that communities in southern Iowa with drinking water supplies contaminated with herbicides have elevated rates of IUGR compared to neighboring communities with different water supplies. Because of the limitations of the ecologic design of this study, including aggregate rather than individual measures of exposure and limited ability to control for confounding factors related to source of drinking water and risk of IUGR, a strong causal relationship between any specific water contaminant and risk of IUGR cannot yet be inferred. The association between the water supplied to the Rathbun communities and the increased risk of IUGR should be considered a preliminary finding that needs to be verified by more detailed epidemiologic studies.

Experimentally induced Chiari-like malformation with myeloschisis in chick embryos.

Though several pathogenetic theories concerning the frequent association of Chiari malformation and hydrocephalus with myeloschisis have been suggested, none of them explains all the aspects of the disorder. To investigate whether myeloschisis is the direct cause of Chiari malformation and hydrocephalus or these conditions are the results of another basic event, we observed the morphological changes of the posterior cranial fossa and its components in the chick embryos with surgically induced myeloschisis. To make myeloschistic lesions, we opened the neural tube for a length of 9-11 somites in Hamburger and Hamilton stage 16-19 chick embryos. They were divided into cervicothoracic (C-T) and lumbosacral(L-S) groups according to the area of incision. The embryos were re-incubated until postoperative day 11. In the control group, embryos were incubated with the eggshell window open as their experimental counterparts. The survival rates of each group were as follows; 11% (9 survivors/85 operated embryos), 8% (7/83), and 17% (10/60) in the C-T, L-S and control groups, respectively. Myeloschisis positive rates were 100% in the operated groups and 0% in the control group. The heads of embryos were sectioned along the sagittal plane to observe the morphological changes in the posterior cranial fossa and its components. Of the survivors, five in the C-T group, two in the L-S group and six in the control group were available for light microscopic inspection. In the majority of embryos with myeloschisis, without difference between the C-T and L-S groups, the fourth ventricles were smaller than those of the control group and the subarachnoid spaces in the posterior cranial fossa were also narrower. In embryos with severe changes, the cerebellum displaced downward comparing with that of the control embryos. No evidence of hydrocephalus was present Though not always typical, morphological changes similar to Chiari malformation were observed in chick embryos with surgically induced myeloschisis. It suggests a strong direct causal relationship between the two conditions and supports the theories of derangements in cerebrospinal fluid dynamics rather than those of primary mesenchymal or neural origin as a pathogenetic mechanism of Chiari malformation.

Climatic factors associated with the infection of herds of cattle with bluetongue viruses.

The incidence of bluetongue virus infection of 15 cattle herds in Queensland, Australia, was determined by a serum neutralization test. The maximum temperature (degree C), minimum temperature (degree C) and rainfall (mm) data were obtained from the meteorological recording stations closest to each herd. Using unweighted least-squares regression analysis, the best statistical model explaining the most variability in the herd incidence rate included the ratio between the maximum and minimum temperature recorded at both 1 month and 6 months preceding seroconversion, and rainfall recorded at both 2 months and 6 months preceding seroconversion. More than 90% of the variability in the incidence of bluetongue virus infection in the herds was explained by the model, a considerable improvement on previous models that used prevalence data. The prospective nature of the study also supports a strong causal relationship between climatic factors and the occurrence of infection in cattle herds.

Evidence for the role of the sheep biting-louse Bovicola ovis in producing cockle, a sheep pelt defect

The prevalence and severity of cockle, a sheep pelt defect characterised by raised lumps, was assessed on lambs that were either louse-infested ( Bovicola ovis) or louse-free at birth. Assessments were made on pickled pelts, 10 months after the lambs had entered the trial. Lambs kept free of lice did not develop cockle, whereas the defect was common in lambs (about 90%) that were infested with lice. There was a direct correlation between louse scores and cockle, high louse scores being associated with a more severe degree of cockle. The results give support to the strong causal relationship between B. ovis and cockle, but questions such as the minimum number of lice needed to cause cockle and the time required for cockle to develop still need to be answered.

Education and the ability to export manufactures: The relevance to South Africa of the Wood model

According to Wood there is a strong causal relation between education of the population and exports of manufactures. Also, a country that is rich in natural resources will tend to have low manufactured exports, which will be exacerbated by low investment in education. Wood's model is applied to South Africa. Increasing the education of the population will be crucial for expanding higher‐value‐added manufactured exports, increasing per capita incomes and reducing earnings inequality in South Africa.

副作用文献情報データベースの利用性と収録情報の評価に関する検討

Monitoring of the literature on adverse reactions over a period of many years is undertaken by the drug information (DI) service as one aspect of drug monitoring, and the formation of a database for more effective utilization of the collected and evaluated information was attempted. The set items include the title of the literature reference, the source, abstract, generic and brand name of drugs and the names of their manufacturers, therapeutic category and adverse reaction symptoms. These items can be retrieved individually or in various combinations.Therefore, when retrieval was done by therapeutic category, drug and adverse reaction symptoms were undertaken for 661 items of information in the adverse reaction literature added to the database in 1989. The system was evaluated, making retrieval of adverse reaction symptoms, which was difficult using conventional procedures, possible instantaneously. This result confirmed that the applicability of system was satisfactory. In a comparison of the information in the database with the contents of package inserts and foreign compendia and a study of evaluations of the information, it was possible to rapidity collect information on severe or new adverse reactions not found in package inserts, etc., and some of these showed a rather strong causal relation with the drug concerned. Therefore, this database appeared to be useful source of information.

Elevated concentrations of ascorbate and normoxia suppress testosterone production in cultured guinea pig leydig cells

In recent years, several metabolic roles have been proposed for vitamin C. Recent information suggests a strong causal relationship between high endogenous levels of ascorbic acid and changes in normal reproductive biology. Using highly enriched populations of guinea pig Leydig cells, we have found that elevated levels (50 to 500 μM) of ascorbate significantly ( P < 0.01) depressed testosterone production in a dose-dependent manner while low levels (0 to 10 μM) were without effect. Leydig cells incubated under hypoxic (3% oxygen) culture conditions produced significantly ( P < 0.01) more testosterone than similar cells cultured under normoxic (19% oxygen) conditions. The results of this study suggest that high concentrations of ascorbate and normoxic culture conditions suppress testosterone production in isolated Leydig cells. Thus, it would seem that there exists a delicate balance between normal metabolic requirements for vitamin C and excessive ascorbate levels that might alter normal gonadal reproductive events.

Causality and Efficiency in the Coffee Futures Market

Tests for causality and rationality in the coffee futures market were carried out using data from the New York Market. Tests of causality indicated that futures prices strongly influence variations in spot price eight weeks or more to maturity. However, beginning seven weeks to maturity there seems to be a strong causal relationship going from futures to spot and from spot to futures. Risk constancy or neutrality, equality of risk premium and spot price, and efficiency were rejected for the period 18, 51, and 33 weeks or more to maturity. However, simultaneity of risk neutrality and efficiency was accepted for contracts with 55-77 weeks to maturity. The general conclusion from this study is that coffee futures market can be used as an indicator of spot market prices for contracts with 55-77 weeks to maturity. While benefits can be obtained through short term adjustment of available stock and making use of quality storage facilities, planning longer term planting and marketing decisions (e.g., ≥ 77 weeks) on the basis of futures market price can result in misallocation of resources and welfare loss.

Regulation of glycolytic flux in Brochothrix thermosphacta by the cytoplasmic pH and adenylate charge: an in vivo NMR study.

Changes in the concentration of inorganic phosphate (Pi) sugar phosphate, phosphoenol pyruvate (PEP), the adenylate charge and pH were followed by 31P-NMR and assay of cell extract during glucose fermentation in Brochothrix thermosphacta. These changes provide an estimation of glycolytic flux via pyruvate kinase as opposed to cycling of PEP through the phosphotransferase system. There appears to be a strong causal relationship between the reduced pH, the high NTP level and the apparent reduction in pyruvate kinase activity, which support the contention that synergistic effect of pH and ATP on pyruvate kinase is an important regulatory factor in these cells.

漫出性中耳炎に伴う感音難聴の臨床統計的検討

It is pointed out that sensorineural hearing loss sometimes accompanies otitis media with effusion. In order to clarify the incidence and clinical features of sensorineural hearing loss associated with otitis media with effusion, the cases over the past ten years were reviewed. During the period from January 1979 through December 1988, 1338 patients were diagnosed to have otitis media with effusion and showed reliable audiograms in our clinic. Among these patients, 237 patients (17.7%) showed sensorineural hearing loss, defined as a bone conduction loss of 25 dB or more at any one of the frequencies of 500 through 4 kHz. The incidence of sensorineural hearing loss increased as the age of the patients increased. By analyzing their clinical course, these 237 patients were classified into 3 groups according to the etiological relationship of sensorineural hearing loss and otitis media with effusion. In Group A which comprises 14 patients (1.0%), a strong causal relationship was suspected. This group was further divided into 2 subgroups. In one subgroup of 4 patients, sensorineural hearing loss developed rather rapidly during the course of otitis media with effusion and recovered gradually. In the other subgroup of 10 patients, sensorineural hearing loss progressed and did not recover. The clinical features of these 2 subgroups were quite different. In Group B which comprises 50 patients (3.7%), causal relationship was suspected but was not confirmed. Many of the patients in this group showed unilateral otitis media with effusion and the sensorineural hearing loss in the same ear, which was characteristically demonstrated as bone conduction loss at 2 and 4 kHz.(ABSTRACT TRUNCATED AT 250 WORDS)

Cigarette Smoking and Risk of Stroke in Middle-Aged Women

It is known that cigarette smoking is associated with increased risk of both thrombotic and hemorrhagic stroke among men. To test for such an association among women, we examined the incidence of stroke in relation to cigarette smoking in a prospective cohort study of 118,539 women 30 to 55 years of age and free from coronary heart disease, stroke, and cancer in 1976. During eight years of follow-up (908,447 person-years), we identified 274 strokes, comprising 71 subarachnoid hemorrhages, 26 intracerebral hemorrhages, 122 thromboembolic strokes, and 55 strokes about which information was insufficient to permit classification. The number of cigarettes smoked per day was associated positively with the risk of stroke. Compared with the women who had never smoked, those who smoked 1 to 14 cigarettes per day had an age-adjusted relative risk of 2.2 (95 percent confidence interval, 1.5 to 3.3), whereas those who smoked 25 or more cigarettes per day had a relative risk of 3.7 (95 percent confidence interval, 2.7 to 5.1). For women in this latter group, the relative risk of subarachnoid hemorrhage was 9.8 (95 percent confidence interval, 5.3 to 17.9), as compared with those who had never smoked. Adjustment for the effects of relative weight, hypertension, diabetes, history of high cholesterol, previous use of oral contraceptives, postmenopausal estrogen therapy, and alcohol intake did not appreciably alter the association between cigarette use and incidence of stroke. These prospective data support a strong causal relation between cigarette smoking and stroke among young and middle-aged women.

Cigarette smoking and risk of stroke in middle-aged women.

It is known that cigarette smoking is associated with increased risk of both thrombotic and hemorrhagic stroke among men. To test for such an association among women, we examined the incidence of stroke in relation to cigarette smoking in a prospective cohort study of 118,539 women 30 to 55 years of age and free from coronary heart disease, stroke, and cancer in 1976. During eight years of follow-up (908,447 person-years), we identified 274 strokes, comprising 71 subarachnoid hemorrhages, 26 intracerebral hemorrhages, 122 thromboembolic strokes, and 55 strokes about which information was insufficient to permit classification. The number of cigarettes smoked per day was associated positively with the risk of stroke. Compared with the women who had never smoked, those who smoked 1 to 14 cigarettes per day had an age-adjusted relative risk of 2.2 (95 percent confidence interval, 1.5 to 3.3), whereas those who smoked 25 or more cigarettes per day had a relative risk of 3.7 (95 percent confidence interval, 2.7 to 5.1). For women in this latter group, the relative risk of subarachnoid hemorrhage was 9.8 (95 percent confidence interval, 5.3 to 17.9), as compared with those who had never smoked. Adjustment for the effects of relative weight, hypertension, diabetes, history of high cholesterol, previous use of oral contraceptives, postmenopausal estrogen therapy, and alcohol intake did not appreciably alter the association between cigarette use and incidence of stroke. These prospective data support a strong causal relation between cigarette smoking and stroke among young and middle-aged women.

Gender and Achievement Status Differences on Learning Factors Among Black High School Students

AbstractRecent investigations have established strong causal relationships between higher achievement outcomes among students and their increased use of specific learning strategies and meta-cognitive processes. Moreover, it has become increasingly evident that even the lowest achieving students can be taught to improve their achievement outcomes through the use of specific learning strategies. Yet, among Black high school students in urban schools and especially among Black high school males, achievement outcomes continue to be disappointingly low. The authors felt that an examination of the use of learning strategies among a sample of these students might provide some useful information. The present study examined differences between high, average, and low achieving Black male and female high school students on measures of learning and study behavior, as well as on motivation and attitude. The results indicated significant differences between high and low achievers and between male and female students o...