Significant Effects Of Independent Variables Research Articles

Eco-Innovation Drivers and Their Impact on Tourism and the Hospitality Business in Egypt

This research aims to examine the mediating effects of eco-innovation practices in the relationship between the drivers of eco-innovation and the performance of tourism and hospitality enterprises. A quantitative approach was adopted in this research using questionnaire surveys as an instrument for collecting primary data. Based on the convenience sampling technique, a total of 550 questionnaire forms were distributed to five-star hotels and travel agencies in Cairo. Out of the distributed forms, only 400 forms were filled out and returned to the researchers and thus valid for analysis, representing a response rate of 72.7%. Structural Equation Modeling (SEM) using partial least squares (PLS-SEM) was employed to test the research model. The results showed the significant effect of independent variables on dependent variables through mediating variables. Multiplied path coefficients were used to measure the confidence interval (CI) for measuring the mediating relationship. The results supported the effect of eco-innovation practices as a mediating factor in the relationship between the drivers of eco-innovation and the performance of tourism and hospitality enterprises. The findings also showed that the eco-innovation drivers, which include management awareness, organizational capabilities, and environmental strategy, have a significant effect on eco-innovation practices and tourism/hospitality enterprise performance when integrating the mediating variables of eco-innovation practices. There are a few studies that have also examined a conceptual framework to examine eco-innovation practices as mediating factors in the relationship between the drivers of eco-innovation and the performance of tourism and hospitality enterprises in terms of five-star hotels and travel agencies in Egypt. Consequently, this research contributes to the literature related to tourism and hospitality management through highlighting the mediating effect of eco-innovation practices on the relationship between the drivers of eco-innovation and the performance of tourism and hospitality enterprises.

Spatial and Numerical Abilities as Correlates of Academic Achievement in Economics

The school system's primary concern and essential function are improving students' academic performance and producing a pool of skilled human resources to help grow and develop a nation. Despite how vital economics is to society, several factors determine students' choices and interests, among which spatial and numerical abilities are significant. This has led to students’ inability to cope with real-life situations, self-independent, and basic entrepreneurial skills. The paper examined spatial and numerical abilities as correlates of academic achievement in Economics. Four research questions guided the study with three instruments to collect data analyzed using mean, standard deviation, and regression analysis at a 0.05 significance level. The results revealed that the mean of all items is higher than the criterion mean of 0.50. Students had a high level of spatial ability (0.50 < 0.91), but performance in numerical ability was poor (0.50 > 0.43). The relationship between the independent variable revealed a significant positive relationship (r= 0.17, p<0.05(0.00)). There was a significant effect of independent variables on the dependent variable (F(2,997)= 41.093; p<0.05(0.000)). Teachers should be trained on how to incorporate spatial ability in economics classes.

Formulation and Evaluation of Niosomal Gel Loaded with Asparagus racemosus Extract for Anti-inflammatory Activity

Abstract: Background/Aim: Inflammation typically occurs when infectious microorganisms enter the body, settle in specific tissues, and/or circulate in the blood. Asparagus racemosus extract contains various saponins and flavonoids and plant-origin drugs have fewer side effects and toxicity. The phytoconstituents have less permeability through the skin; to enhance their permeability and effectiveness it was loaded in niosomes. Therefore, the study aimed to formulate and characterize the niosomal gel loaded with Asparagus racemosus extract for anti-inflammatory activity. Materials and Methods: The niosomes containing saponins in the extract were prepared using thin film hydration method and 23 full factorial design was employed to assess the influence of independent variables span 60 and cholesterol on vesicle size, PDI, zeta potential, and percentage entrapment efficiency. 10% of niosomal and conventional gels were prepared by incorporating optimized niosomes and extract containing total saponin in 1% carbopol gel. Ex vivo permeability studies of prepared gels were performed through goat skin using Franz diffusion cell. An anti-inflammatory study was conducted on albino rat. Results: The statistical analysis revealed the significant effect of independent variables on vesicle size, PDI, entrapment efficiency and zeta potential. SEM image shows vesicles are spherical in shape and uniform in size. The niosomal gel provided a significantly higher amount of steady-state flux and permeability coefficient into the skin than conventional gel. The animal model proved that niosomal gel loaded with total saponins in extract showed significant anti-inflammatory compared to the control. Conclusion: It was concluded that the niosomal gel had better efficacy than the conventional gel. Keywords: Asparagus racemosus, Niosomes, Span 60, Cholesterol, Factorial design, Carbopol 934.

Reasons and Opinions of Students Learning English as a Foreign Language about Learning the Target Culture

This study aims to compare the opinions of optional and compulsory preparatory class students about learning English and the target culture. Furthermore, students’ reasons to learn English are examined in terms of independent variables (gender, going abroad and status of prep class). In the present study, data are gathered through a questionnaire in the fall term of 2021-2022 academic year. Data are obtained from 150 participants and analyzed via SPSS 25. Descriptive statistics and inferential statistics are conducted. Findings show that students are motivated to learn English both instrumentally and in an integrative way. In addition, there is no statistically significant effect of independent variables on the reasons to study English and the attitudes towards learning English and the target culture. As a result, this current study offers guidance for teachers while they are preparing their teaching materials. That is, teachers should consider not only the culture of British or American but also they should focus on other cultures.

Effects of various milk powders on main quality parameters of cocoa butter substitute-based chocolate

Optimal conditions for formulation of cocoa butter substitute (CBS)-based milk chocolate produced in a ball mill with hydrogenated palm kernel oil stearin as CBS were defined using a D-optimal mixture design. In the formulation of chocolate samples, various amounts of whole milk powder, skimmed milk powder and demineralised whey powder were used and their effect on physico-chemical, colour, texture, and sensory properties were investigated. The fitted models demonstrated significant effects of independent variables on various quality parameters. Optimum formulation for selected parameters to maximise taste and minimise whole milk powder content as well as reduce costs were determined. Moreover, the optimum formulation was produced to validate the optimum model. Results of the validation were consistent with the findings of the model study. Furthermore, the approach used in this work could be employed to develop strategies to produce CBS-based milk chocolate with lower costs and various quality properties.

The effect of meteorological parameters on PM2.5 concentration changes in 2018 (Case study: Tehran)


 
 
 
 Introduction: Studies in different parts of the world have shown that exposure to air pollutants has a negative effect on human health.
 Materials and methods: For statistical analysis between the dependent variable Particulate Matter less than 2.5 μm (PM2.5) concentration and independent variables (wind speed, precipitation, humidity, and temperature) R version 3.6.2 was used. Spearman correlation coefficient was used to determine the correlation between the parameters with the dependent variable. In addition, the multiple linear regression model was used to investigate the relationship and prediction between the independent variables and the dependent variable. In the present study, the effect of meteorological parameters on PM2.5 concentration in different seasons in Tehran in 2018 was studied using Pearson correlation and linear regression statistical analyzes.
 Results: Based on the results, it was found that PM2.5 had no significant relationship with meteorological parameters. Only in summer, there was a significant relationship between the dependent variable and the independent variable (wind speed) (p-value=0.01) and there was also an inverse relationship between these variables (r=-0.65). Multiple linear regression was also used to investigate the significant effect of independent variables on the dependent variable.
 Conclusion: According to the coefficients of determination in this model, 47, 16, 45, and 20% of the dependent variable change in autumn, winter, spring, and summer, respectively, can be explained by meteorological parameters (independent). Due to the fact that the concentration of PM2.5 in Tehran is higher than the national standard, more attention of officials is necessary to improve air quality in Tehran.
 
 
 

Quality by Design Approach to Formulate Empagliflozin-Loaded Chitosan Nanoparticles: In Vitro, In Vivo and Pharmacokinetic Evaluation of Anti-Diabetic Drugs

Present research focuses on formulating the empagliflozin (EMPA) loaded chitosan nanoparticles (CS Nps) using quality by design approach to overcome its innate adverse effects and enhance therapeutic prospects. Box- Behnken design (BBD) suggested quadratic model for fabricating EMPA Nps, by ionic gelation method, showing significant effect of independent variables on responses. The particle size and polydispersity index (PDI) for formulated EMPA loaded CS Nps was 152.4 ± 0.84 nm and 0.245 ± 0.005, respectively. The % entrapment efficiency and loading capacity of EMPA Nps was 83.8 ± 0.002% and 42.9 ± 0.03 %. Surface morphology of Nps using TEM, DSC and FTIR spectra of pure drug and formulated Nps were studied for further characterization. In vitro release of EMPA CS Nps showed better release profile than pure EMPA solution when compared in 2 different buffers namely; Phosphate buffer pH 7.4 (85.19 ± 4.22 %) and HCl buffer pH 1.2 (86.68 ± 7.33%). Permeability coefficient enhanced by 6.2-fold in case of EMPA CS Nps attributing to increase in intestinal uptake owing to small particle size. The study of pharmacokinetic parameters showed increase in plasma concentration and elimination half -life of EMPA Nps when compared to EMPA suggesting better distribution of drug inside the systemic circulation. The stability study conducted for 90 days showed no variations in the physical stability of Nps. The application of quality by design approach for EMPA loaded CS NPs showed improved permeation, drug release and better pharmacokinetic profile proposing CS as a promising carrier of EMPA for the better efficacy, leading to prospective clinical fate.

Extraction of phenol compound from Mentha piperita by ultrasonic waves based on a response surface methodology.

In this study, optimization of the extraction of phenol compounds from Menthapiperita using ultrasonic waves with response surface methodology (RSM) was assessed. In this regard, a central composite design with three independent variables of time (5, 27.5, and 50min), temperature (25, 45, and 65°C), and concentrations of ethanol in the water-ethanol solution (0%, 50%, and 100%) was used. Besides, the antioxidant activity tests (DPPH radical scavenging assay, ferric reducing antioxidant power [FRAP], and oxidative stability indexes [OSI]) were examined. Significant effects of independent variables on the extraction of phenol compound, DPPH radical scavenging power, and OSI of M.piperita extract, with the regression coefficients of 0.89, 0.92, and 0.94, respectively, were noted. However, no significant difference in terms of the FRAP among different treatments was noted. Also, the best antioxidant activity of M.piperita was obtained by using the ultrasonic wave for 50min at 65°C and 59.6% v/v ethanol/water solution. While the findings of RSM confirmed the experimental results, due to the favored properties of M.piperita extract by the proposed method, further research to investigate possible applications in the food industry is recommended.

Digestate residues analysis under elevated heat regime by using DNS method

The problems with unsorted municipal waste are always associated with disposal issues as it requires a large area for landfilling or high energy used for incineration. In recent years, an autoclaving technique has been considered a promising approach which could minimize the volume of organic waste from being directly disposed or incinerated. In this work, an attempt was done to study the saccharification potential of organic residues under elevated temperature Thermal treatment involving hot water bath was applied to treat the organic residue ranging from 60oC to 100oC for 30 and 60 minutes. The result obtained showed an increasing trend for the concentration of glucose and carbohydrate. However, the result for lignocellulose content which contains various component includes extractive, holocellulose, hemicellulose, cellulose and lignin show variation. Based on the thermal treatment carried out, the result indicated that the trend of glucose and carbohydrate content. The highest percentage of glucose that can be obtained 978.602 µg/ml which could be obtained at 90oC at 60 minutes. The carbohydrate also shows an increasing trend with 0.234 mg/ml as the highest peak achieved at 80oC for 30 minutes treatment. However, it was found that the lignocellulose content varies with temperature and time. The statistical analysis was carried out using two-ways ANOVA shows an interaction effect between the independent variables (temperature and contact time) and the saccharification effects on the food wastes. The result shows a variation in the significant effect of independent variables on the changes in the composition of food waste.

PENGARUH KEPEMIMPINAN DAN KOMUNIKASI TERHADAP KINERJA KARYAWAN PADA FAVE HOTEL KUTA KARTIKA PLAZA

Employee performance is a very important thing in the organization's business to achieve company goals so that various activities must be carried out by the company to achieve its objectives and continue to improve the performance of its employees, one of which is to set appropriate performance standards and performance appraisal. This study aims to determine whether or not there is a simultaneous or partial influence between leadership and communication on employee performance at Fave Hotel Kuta Kartika Plaza. This research was also conducted to find out which variables had a more dominant influence on employee performance at Fave Hotel Kuta Kartika Plaza. The respondents of this study were 65 employees of Fave Kuta Hotel Karika Plaza. The data analysis technique used is multiple linear regression analysis techniques. T test is used to determine the effect of independent variables on the dependent variable partially and the F test is used to determine the significant effect of independent variables on the dependent variable together (simultaneous). Based on the results of the analysis, it is known that leadership and communication together have a significant effect on the performance of employees of Fave Hotel Kuta Kartika Plaza. This can be seen from the results of the t test, the leadership and communication variables partially have a positive effect on employee performance, where leadership has a value of t arithmetic (8,035)> t table (1,670). Furthermore, the F test is where F count 38.081> from the value of F table 3.145 while the most dominant variable influencing employee performance is the leadership variable of 0.686> of the communication variable 0.348. Based on the results of the study, it can be suggested that company leaders are expected to be more open in giving directions to subordinates, good and effective communication so that they continue to be intertwined between superiors and subordinates or fellow employees in the company.

Applying Multivariate and Univariate Analysis of Variance on Socioeconomic, Health, and Security Variables in Jordan

Many researchers have studied socioeconomic, health, and security variables in the developed countries; however, very few studies used multivariate analysis in developing countries. The current study contributes to the scarce literature about the determinants of the variance in socioeconomic, health, and security factors. Questions raised were whether the independent variables (IVs) of governorate and year impact the socioeconomic, health, and security dependent variables (DVs) in Jordan, whether the marginal mean of each DV in each governorate and in each year is significant, which governorates are similar in difference means of each DV, and whether these DVs vary. The main objectives were to determine the source of variances in DVs, collectively and separately, testing which governorates are similar and which diverge for each DV.
 The research design was time series and cross-sectional analysis. The main hypotheses are that IVs affect DVs collectively and separately. We carried out Multivariate and univariate analyses of variance to test these hypotheses. The population of 12 governorates in Jordan and the available data of 15 years (2000–2015) accrued from several Jordanian statistical yearbooks. We investigated the effect of two factors of governorate and year on the four DVs of divorce, mortality, unemployment, and crime. We used the rate of divorce, mortality, and crime, and the percentage of unemployment in the analyses. We transformed all DVs to multivariate normal distribution. We calculated descriptive statistics for each DV in each governorate and each year. We provided visual and numerical inspection of how each DV changed over time in each governorate compared with DV change in other governorates.
 Based on the multivariate analysis of variance, we found a significant effect in IVs on DVs with p < .001. Based on the univariate analysis, we found a significant effect of IVs on each DV with p < .001, except the effect of the year factor on unemployment, was not significant with p = .642. The grand and marginal means of each DV in each governorate and each year were significant based on a 95% confidence interval. Most governorates are not similar in DVs with p < .001.
 We concluded that the two factors produce significant effects on DVs, collectively and separately. Based on these findings, the government can distribute its financial and physical resources to governorates more efficiently. By identifying the sources of variance that contribute to the variation in DVs, insights can help inform focused variation prevention efforts.

FORMULATION AND OPTIMIZATION OF MUCOADHESIVE MICROSPHERES OF VALSARTAN BY USING BOX-BEHNKEN DESIGN

Objective: The purpose of this study was to formulate and optimize mucoadhesive microspheres of antihypertensive drug (valsartan) within ethyl cellulose as a carrier polymer and carbopol 934P as a mucoadhesive polymer for controlling the release of valsartan.
 Methods: The emulsion solvent evaporation technique was used for preparation of microspheres of valsartan and the Box-Behnken design was employed with thee independent variables that is amount of ethyl cellulose (X1) and amount of carbopol 934P (X2) and stirring speed (X3) and evaluate four dependent variables such as percentage mucoadhesion, Q1 h, t90% and drug entrapment efficiency.
 Results: The optimum conditions were found to be X1= 200 mg, X2= 107 mg and X3= 1200rpm. The optimized batch exhibited a high drug entrapment efficiency of 85.63±1.384%, percentage mucoadhesion was 66.76±0.986% and drug release was also sustained for more than 12 h.
 Conclusion: The analysis of variance showed a significant effect of independent variables. The scaning electron microscopy (SEM) analysis showed that the microspheres were spherical and free-flowing. The microspheres of valsartan were stable after thee month stability study at accelerated condition.

Evaluating the impact of digital library database resources on the productivity of academic research

PurposeDigital library database resources have a significant impact on stimulating the research culture in higher education. The use of digital databases makes it possible to understand intellectual growth, research productivity, planning and identification of user information needs. Evaluating the effectiveness of user database resource utilization and research, the purpose of this study is to assist management in developing an excellent academic policy.Design/methodology/approachThis study establishes a quantitative method to analyze the productivity of academic research using digital databases. The secondary data extracted from the databases of 52 universities provided by Higher Education Commission (HEC) and the literature published on the Institute of Scientific Information (ISI) Web of Science. The statistical technique simple linear regression was used to analyze the data for understanding the impact of independent variables the “digital databases” on the dependent variable “research productivity”.FindingsThe result of the coefficient of multiple determination,R-squared,R20.679, indicated 67 per cent impact of the predictor on the outcome variable. However, the standardized coefficient Beta 0.824 revealed 82 per cent impact of the individual predictor on the outcome variable. Overall, the result of linear regression showed a significant effect of independent variables on the dependent variable. Besides, the result of correlation and the strength of association between the database resources and the academic publication was significant (p< 0.005).Practical implicationsThis research work is a supportive tool for managing gaps and promoting the development of necessary measures to develop strategies and solutions to create a better academic environment. The ultimate use of standard database resources can foster higher academic research to develop innovative ideas and improve researchers’ cognitive abilities.Originality/valueFrom Pakistan’s point of view, this study is the first one that gives insight into the intellectual growth of young researchers in higher education. The study provides first-hand information on the use of database resources and their significant impact on the productivity of academic research.

Can Capital Structure Affect the Financial Performance of Banks in Turkey?

<p>The aim of this study is to investigate the determinants of banks’ financial performance in terms of the capital structure. Annual financial statements of 11 banks traded in Borsa Istanbul are employed for the period of 2006-2016. Return on assets, return on equity and earnings per share are chosen for financial performance measures. The independent variables related to the capital structure are capital adequacy, equity-to-asset, and financial leverage ratios. In addition, macroeconomic variables and bank-specific variables are also considered as control variables for the analysis. The data are analyzed by the panel data regression analysis as it provides more informative finding and less multicollinearity among variables than time series and cross-sectional analyzes.</p><p>The Hausman test results indicate that the random effects model is appropriate for the whole dependent variables. According to the findings; while equity-to-asset ratio affects return on assets positively, amongst the control variables specific to firms, firm size, asset quality and asset growth variables have significant effects on return on assets. It is found no significant effect of independent variables on return on equity, however, it is seen that asset quality has a negative and significant effect. Inflation and interest rates have a significant effect on both variables. Finally, it is seen that equity-to-asset ratio has a positive and significant effect on earnings per share. Only the effect of asset quality on earnings per share is found to be significant among the control variables. Findings of the study are consistent with the previous studies. In addition, the M&M views are not supported by the findings related to return on assets and earnings per share but the return on equity.</p>

A Review: Model Used for Analyzing Pharmaceuticals Profitability

This paper tried to introduce the model used for analyzing firm performance specific to the pharmaceuticals profitability presenting some company performance analysis models. Empirical evidences shows that firm performance is used as dependent variable represented by Return (R), Return on Assets (ROA), Return on Equity (ROE), Cumulative Abnormal Return (CAR), Profitability Index (PI) and Tobin’s Q. Corporate characteristics and macroeconomic variables are used as independent variables. Corporate characteristics variables are represented by: EBIT Margin, EPS, Net Profit Margin, Current Ratio, Quick Ratio, Debt to Total Assets, Book Value, Country Origin, Drug Type, R&D, Market Share, Imported Technology, Product Life and few dummy variables. Macroeconomic variables like: Inflation, Exchange Rate and Interest Rate. The majority of the studies used multiple regression models for the purpose of identifying the significant effect of independent variables on firm's performance and few studies found using sensitivity and ratio analysis for analyzing pharmaceuticals performance. The article also proposed a new model for analyzing pharmaceuticals profitability.

Can Capital Structure Affect the Financial Performance of Banks in Turkey?

<p>The aim of this study is to investigate the determinants of banks’ financial performance in terms of the capital structure. Annual financial statements of 11 banks traded in Borsa Istanbul are employed for the period of 2006-2016. Return on assets, return on equity and earnings per share are chosen for financial performance measures. The independent variables related to the capital structure are capital adequacy, equity-to-asset, and financial leverage ratios. In addition, macroeconomic variables and bank-specific variables are also considered as control variables for the analysis. The data are analyzed by the panel data regression analysis as it provides more informative finding and less multicollinearity among variables than time series and cross-sectional analyzes.</p><p>The Hausman test results indicate that the random effects model is appropriate for the whole dependent variables. According to the findings; while equity-to-asset ratio affects return on assets positively, amongst the control variables specific to firms, firm size, asset quality and asset growth variables have significant effects on return on assets. It is found no significant effect of independent variables on return on equity, however, it is seen that asset quality has a negative and significant effect. Inflation and interest rates have a significant effect on both variables. Finally, it is seen that equity-to-asset ratio has a positive and significant effect on earnings per share. Only the effect of asset quality on earnings per share is found to be significant among the control variables. Findings of the study are consistent with the previous studies. In addition, the M&M views are not supported by the findings related to return on assets and earnings per share but the return on equity.</p>

Can Capital Structure Affect the Financial Performance of Banks in Turkey?

<p>The aim of this study is to investigate the determinants of banks’ financial performance in terms of the capital structure. Annual financial statements of 11 banks traded in Borsa Istanbul are employed for the period of 2006-2016. Return on assets, return on equity and earnings per share are chosen for financial performance measures. The independent variables related to the capital structure are capital adequacy, equity-to-asset, and financial leverage ratios. In addition, macroeconomic variables and bank-specific variables are also considered as control variables for the analysis. The data are analyzed by the panel data regression analysis as it provides more informative finding and less multicollinearity among variables than time series and cross-sectional analyzes.</p><p>The Hausman test results indicate that the random effects model is appropriate for the whole dependent variables. According to the findings; while equity-to-asset ratio affects return on assets positively, amongst the control variables specific to firms, firm size, asset quality and asset growth variables have significant effects on return on assets. It is found no significant effect of independent variables on return on equity, however, it is seen that asset quality has a negative and significant effect. Inflation and interest rates have a significant effect on both variables. Finally, it is seen that equity-to-asset ratio has a positive and significant effect on earnings per share. Only the effect of asset quality on earnings per share is found to be significant among the control variables. Findings of the study are consistent with the previous studies. In addition, the M&M views are not supported by the findings related to return on assets and earnings per share but the return on equity.</p>

Optimization of olive oil based O/W nanoemulsions prepared through ultrasonic homogenization: A response surface methodology approach

The present study was conducted to prepare co-surfactant free, olive-oil based alpha tocopherol nanoemulsions, using a food grade non-ionic surfactant. Response surface methodology (RSM) was used to determine the effects of independent variables (ultrasonic homogenization time, olive oil concentrations and surfactant contents) on different physico-chemical characteristics of O/W nanoemulsions. This study was carried out using a central composite design. The coefficients of determination were greater than 0.900 for all response variables and there were significant effects of independent variables on all responses. The optimum levels of independent variables for the preparation of nanoemulsions were 3min. ultrasonic homogenization time, 4% olive oil content and 2.08% surfactant concentration. The physico-chemical responses at these levels were 151.68nm particle size, 7.17% p-anisidine and 88.64% antioxidant activity. These results will help in design of nanoemulsions with optimum independent variables.

The Possibility of Using the Internet to Transform the Role of Its Users to Promoters of Medical Products in Jordan

This study aimed to identify the role of Internet technology in transforming the role of its users to promoters of medical products in Jordan. The study found that there are statistically significant effects of independent variables (multipurpose and advanced Internet programs, reduced costs of the use of Internet programs, collective and interactive communication via the Internet, and Internet information abundance and variety of its resources) on the dependent factor, which is transformation of the role of Internet users to promoters of medical products in Jordan. The study recommended increasing attention on networks to promote medical products in Jordan. This is consistent with the fact that promotion via networks has become an effective way to support and enhance the image of products and its delivery to the target group in all markets around the world.

Mathematical modeling of cancer incidence rates: Linear models of colon cancer in connecticut

Mathematical models of cancer incidence were developed to evaluate substantively trends in age and period of diagnosis and to identify differences in these trends with regard to qualitative variables such as sex and anatomical localization of tumor. Parameter estimates were obtained through a weighted least-squares procedure, and hypothesis testing was carried out using minimum modified χ 2 statistics. These procedures were applied to colon cancer incidence rates for Connecticut males and females during the period 1940–1974. The initial model of changes in incidence over calendar time for males and females showed a different pattern and excess risk among males and a possible birth cohort effect among females. The changing pattern of risk in males was modeled as an exponential function of age and a two-stage, age-related process was identified. While proportional comparisons of time trends between the ascending and sigmoid colon showed significant differences for certain groups, patterns in absolute changes were not found to be statistically different. Using mathematical models of cancer incidence rates for substantive analysis can be useful for hypothesis generation in cancer epidemiology. Such modeling proves worthwhile because it allows the investigator to summarize the trends and patterns of cancer incidence through model parameters which then may be tested statistically for the purpose of identifying significant effects of independent variables.