Home About us Contact
|
Home About us Contact | ||
|
|
||
Period Effects (period + effects)
Selected AbstractsAge,environment model for breast cancerENVIRONMETRICS, Issue 3 2004Nobutane Hanayama Abstract In the field of breast cancer study, it has become accepted that crucial exposures to environmental risks might have occurred years before a malignant tumor is evident in human breasts, while age factors such as ages at menstruation have been known as risks for the disease already. To project trends in two such kinds of risks for the disease, the concept of environment effects is introduced for (age, period)-specific breast cancer mortality rates. Also, a new model, named the age,environment (AE) model, which assumes that the logarithm of the expected rate is a linear function of environment effects and age effects, is proposed. It is shown that, although environment effects have different meanings from period effects or cohort effects, in the age,period,cohort (APC) model, the range space of the design matrix for the AE model is included in that for APC model. It is seen, however, that the AE model provides a better fit to the data for females in Japan and the four Nordic countries than does the APC model in terms of AIC. From the results of ML estimation of the parameters in the AE model based on the data obtained in Japan, we see high levels of environment effects associated with the Sino,Japanese war, World War II and the environmental pollution due to the economy in the recovery period from the defeat. Besides, from those based on the data obtained in the four Nordic countries, we see high levels of environment effects associated with the environment becoming worse after the year of Helsinki Olympics and low levels of them associated with the period including the year of ,Miracle of the Winter War' in Finland. Copyright © 2004 John Wiley & Sons, Ltd. [source] Age, period and cohort influences on beer, wine and spirits consumption trends in the US National Alcohol SurveysADDICTION, Issue 9 2004William C. Kerr ABSTRACT Aims To estimate the separate influences of age, period and cohort on the consumption of beer wine and spirits in the United States. Design Linear age,period,cohort models controlling for demographic change with extensive specification testing. Setting US general population 1979,2000. Measurements Monthly average of past-year consumption of beer, wine and spirits in five National Alcohol Surveys. Findings The strongest cohort effects are found for spirits; cohorts born before 1940 are found to have significantly higher consumption than those born after 1946, with especially high spirits consumption for men in the pre-1930s cohorts. Significant cohort effects are also found for beer with elevated consumption in the 1946,65 cohorts for men but in the pre-1940 cohorts for women. Significant negative effects of age are found for beer and spirits consumption, although not for wine. Significant period effects are found for men's beer and wine consumption and for women's spirits consumption. Increased educational attainment in the population over time is associated with reduced beer consumption and increased wine consumption. Conclusions Changing cohort demographics are found to have significant effects on beverage-specific consumption, indicating the importance of controlling for these effects in the evaluation of alcohol policy effectiveness and the potential for substantial improvement in the forecasting of future beverage-specific consumption trends, alcohol dependence treatment demand and morbidity and mortality outcomes. [source] Effects of season, variety and botanical fractions on oxalate content of napiergrass (Pennisetum purpureum Schumach)GRASSLAND SCIENCE, Issue 4 2006M. M. Rahman Abstract Various tropical grasses sometimes contain oxalate in sufficient concentration as to induce calcium deficiency in grazing animals. Napiergrass (Pennisetum purpureum), a useful tropical grass for ruminants was examined for oxalate levels with regard to season, variety and botanical fractions. It was observed that oxalate content was significantly (P < 0.001) affected by the season with the highest value (3.77%) being associated with early summer samples and the lowest value (1.76%) with late autumn samples. Compared to a normal, non-dwarf variety, a dwarf variety exhibited a higher oxalate content but the difference was not statistically significant. With regard to the botanical fractions, oxalate content was significantly (P < 0.05) higher (2.78%) in leaf tissues compared to stem with leaf sheath (2.05%). In another experiment, a late, dwarf variety was re-grown four times to evaluate re-growth period effects on oxalate content during the early summer. Oxalate content increased gradually from the re-growth period 1 (6 June to 28 June) to re-growth period 3 (21 June to 12 July), and declined in re-growth period 4 (28 June to 19 July). Results suggest that when napiergrass is grown in early summer, it could achieve oxalate levels that are toxic to ruminants. [source] An empirical analysis of US and Japanese health insurance using age,period,cohort decompositionHEALTH ECONOMICS, Issue 5 2007Kosei Fukuda Abstract Aggregate data on household health insurance expenditure in the US and Japan that are classified by period and age are decomposed into age, period, and cohort effects by using the Bayesian cohort models. These models are developed to overcome the identification problem involved in cohort analysis. Despite the differences between the health insurance systems of the two countries, three interesting empirical findings are obtained. First, in both the countries, the age effects are the most influential, and the cohort effects have negligible influence. The latter provides a striking policy implication since the generational imbalance in social security expenditures is widely recognized in developed countries. Second, in both the countries, the period effects show a roughly upward trend. Finally, the age effects exhibit a roughly upward movement for all age groups in the US; however, in Japan, these effects show a downward movement for the 55,59 age group due to the changes in the health insurance system on retirement. Copyright © 2006 John Wiley & Sons, Ltd. [source] Increasing incidence of non-Hodgkin's lymphoma in Canada, 1970,1996: age,period,cohort analysisHEMATOLOGICAL ONCOLOGY, Issue 2 2003Shiliang Liu Abstract Previous studies have shown that the incidence of non-Hodgkin's lymphoma (NHL) has increased in many parts of the world in recent decades. Using data obtained from the Canadian Cancer Registry, the present study examined time trends in NHL incidence in Canada between 1970 and 1996 and the effects of age, period of diagnosis and birth cohort on incidence patterns for each sex separately. Results showed that overall age-adjusted incidence rates increased substantially, from 7.3 and 5.2 per 100,000 in 1970,1971 to 14.0 and 10.0 per 100,000 in 1995,1996 in males and females, respectively. Diffuse lymphoma was the major histological subtype, accounting for approximately 76% of NHL cases over the 27-year period. The data suggest that period effects have played a major role, although birth cohort effects may also have been involved. Sex-specific patterns of the incidence were similar over the time period of diagnosis but were distinct among recent birth cohorts. In conclusion, there is in fact a marked increase in NHL in Canada which cannot be explained in terms of improvements in diagnosis, changes in NHL classification and the increase in AIDS-associated NHL alone. The birth cohort effect in NHL suggests that changes in risk factors may have contributed to the observed increase. Copyright © 2003 John Wiley & Sons, Ltd. [source] A methodology using subjective and objective measures to compare plaque inhibition by toothpastesJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 12 2004N. Claydon Abstract Objectives: Plaque scoring usually employs subjective indices. The aim was to compare plaque inhibition of three toothpastes using two objective and one subjective measures of plaque. Material and Methods: Formulations were: (1) an experimental anti-plaque paste (test); (2) an experimental paste (minus active or negative control); and (3) a proprietary anti-plaque toothpaste product (positive control). The study was a blind, randomised crossover design using a 4-day, no tooth brushing, plaque regrowth model and involving 22 healthy subjects. After baseline plaque removal, subjects rinsed twice a day with slurries of the allocated paste. On day 5, plaque was scored by index, wet weight and optical density of extracted disclosing solution from the plaque (stain intensity). Results: All data showed the same pattern. There were highly significant subject and treatment effects but not period effects. The positive control was highly significantly more effective in plaque control than the test and minus active experimental formulations, which in turn were not significantly different from each other. There were strong and significant correlations between pairs of scoring methods particularly wet weight and stain intensity. Conclusion: The use of objective methods of plaque alongside conventional subjective indices provided convincing evidence for increased discriminatory power in a study comparing plaque inhibition by toothpastes. [source] Estimating price and income elasticities in the presence of age-cohort effectsAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 2 2006Hiroshi Mori Individual consumption of most food products varies by age, and in countries like Japan that have experienced drastic social and economic changes during the past several decades, it also differs from generation to generation. Unless proper measures are taken to account for these factors, estimates of demand elasticities could be severely biased. In this study, individual consumption of fresh fruit was derived from Japanese household data classified by age of household head for the years 1979,2001. Individual consumption was then decomposed by age, cohort, and period effects using Bayesian cohort analysis. Pure period effects thus determined were regressed against changes in price and income, to obtain less biased estimates for demand parameters than non- or partially age-compensated analysis. [Econlit citations: Q110]. © 2006 Wiley Periodicals, Inc. Agribusiness 22: 201,217, 2006. [source] Unemployment and Earnings Assimilation of ImmigrantsLABOUR, Issue 3 2002Pål Longva The regional unemployment elasticity of annual earnings for non-OECD immigrants is found to be more than three times larger than for natives, using micro data covering all immigrants in Norway in 1990 and a random sample of natives. The decline in relative earnings of non-OECD immigrants from 1980 to 1990 can largely be explained by the stronger impact of rising unemployment on immigrant earnings. These results highlight the importance of controlling for different period effects caused by fluctuating unemployment in panel studies of earnings assimilation among immigrants. [source] The trend of mean BMI values of US adults, birth cohorts 1882,1986 indicates that the obesity epidemic began earlier than hitherto thoughtAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2010John Komlos Background: The trend in the body mass index (BMI) values of the US population has not been estimated accurately because the time series data are unavailable and the focus has been on calculating period effects. Objectives: To estimate the trend and rate of change of BMI values by birth cohorts stratified by gender and ethnicity born 1882,1986. Methods: We use loess additive regression models to estimate age and trend effects of BMI values of US-born black and white adults measured between 1959 and 2006. We use all the National Health Examination Survey and National Health and Nutrition Examination Survey data. Results: The increase in BMI was already underway among the birth cohorts of the early 20th century. The rate of increase was fastest among black females; for the three other groups under consideration, the rates of increase were similar. The generally persistent upward trend was punctuated by upsurges, particularly after each of the two world wars. The estimated rate of change of BMI values increased by 71% among black females between the birth cohorts 1955 and those of 1965 is indicative of the rapid increases in their weight. Conclusions: We infer that transition to postindustrial weights was a gradual process and began considerably earlier than hitherto supposed. Am. J. Hum. Biol. 22:631,638, 2010. © 2010 Wiley-Liss, Inc. [source] A COHORT ANALYSIS OF US AGE,EARNINGS PROFILESBULLETIN OF ECONOMIC RESEARCH, Issue 2 2008Kosei Fukuda J31; C51 ABSTRACT Aggregate data on US earnings, classified by period and by age, are decomposed into age, period and cohort effects, using the Bayesian cohort models, which were developed to overcome the identification problem in cohort analysis. The main findings, obtained by comparing college and high school graduates, are threefold. First, the age effects show a downward trend for the age group of 45,49 onwards for high school graduates but do not show any such trend for college graduates. Second, the period effects show a downward trend for high school graduates but reveal no such trend for college graduates. Third, the cohort effects are negligible for both college and high school graduates. [source] | |||||||||||||