Most literatures on daily water intake are focused on developed countries and to our knowledge; t... more Most literatures on daily water intake are focused on developed countries and to our knowledge; there is limited information on the hydration status of Nigerians. Our objective was to describe daily water intake (DWI) among Nigerian students, develop a model for the prediction of students' DWI and examine the association between DWI and four predictor variables. Data on DWI for 150 students aged 18-26 years were collected through a survey conducted at Kwara State University in February, 2013 together with information on their age, weight, gender and awareness of dieticians' recommendation. Our results indicates that students' DWI varies by gender with male students drinking more than their female counterparts; although, the awareness rate is higher in females than males. We found that nearly half of participants (44%) drank less than 2.7 L of water/day, 25% between 2.7 and 3.7 L/day and 31% reported drinking more than 3.7 L of water/day. Results also revealed that students' DWI decline with age but increases with weight and one-intwo of the students are unaware of the dangers of poor hydration. Arguably, this study is the first description of DWI among Nigerian students and fills the gap in the literature by developing two models for the prediction of students' DWI. In light of the significance of the knowledge and awareness of Dieticians' recommendation on DWI (as evidence in this study) and the low awareness rate existing among the students; nutrition and health promotion program on the benefits of adequate DWI by schools and health organizations is extremely important. This has the potential of improving the health of students.
One of the key issues plaguing the existing studies on the use of the social networking sites (SN... more One of the key issues plaguing the existing studies on the use of the social networking sites (SNSs) is the lack of a uniform index for measuring the time spent on the sites. The present investigation tries to fill this gap by conceptualizing, developing, and validating a new construct, which we referred to as social networking time use scale (SONTUS). To achieve this, two separate studies were conducted. The data for the first study was collected from 2049 individuals through quota sampling approach. Meanwhile, in this first study, we used exploratory factor analysis to identify the dimension of the SONTUS construct. Findings from this study reveal that SONTUS has five factors with good measurement properties. The main aim of the second study (where we utilized data from 1808 people) is to carry out a confirmatory factor analysis (CFA) and tests three hypothesized models. In addition, it aims to investigate the construct validity of SONTUS; and to achieve this, we used 10 personality and well-being measures, and two theoretically related constructs to SONTUS. The CFA results showed that SONTUS has five factor solution consisting of 29 items and that the model with 5 first-order factors with 1 second-order factor is the most suitable model for the study population. Additionally, the second study provides preliminary evidence for the convergent, predictive, and incremental validity of SONTUS. Overall, the findings from our exploratory (study 1) and confirmatory (study 2) studies shows that SONTUS can be used as a standardized instrument for measuring time spent on sites.
With the growing amount of research on the use of technology, especially the mobile phones, the p... more With the growing amount of research on the use of technology, especially the mobile phones, the paucity of research in the area of mobile phone use that focus on the reasons why students use their mobile phones during lecture periods is somewhat surprising. Findings from the previous studies have documented that students continue to use their mobile phones during lecture periods even in classes where its use is banned. Thus, the motives that determine students' continued intention to use their mobile phones during lecture periods becomes an important issue that deserves urgent attention from researchers and education policymakers. In the present investigation, we tried to fill this gap by examining the determinants of students' continuance use of mobile phones during lecture periods. To achieve this, three stages of instrument development (item generation, scale development, and instrument testing) were undertaken through two studies. The results of the exploratory and confirmatory factor analysis confirmed the existence of six dimensions in the proposed measurement instrument (which we referred to as gravitating towards mobile phone (GoToMP)); the dimensions are boredom, class-related use, social connection, emergency, addiction, and perceived behavioral control. The combined findings from the two studies reported here provide initial evidence that GoToMP exhibits excellent psychometric properties and can be used in future empirical research on mobile phone use behaviors of students.
We addressed two shortcomings in the existing studies that focused on the association between stu... more We addressed two shortcomings in the existing studies that focused on the association between students' academic performance (SAP) and their mobile phone use behaviors (MPUB) in this study by conducting a self-report, student-based cross-sectional study in two Nigerian universities between February and March 2014. We collected the data for the study from 286 students in the two universities using a convenience-based sampling approach. The data were analyzed using fsQCA version 2.0 and hierarchical linear (blocked) regression (HLR). The HLR results reveal that time spent calling on phone was the only significant predictor of SAP out of the seven MPUB variables (addiction, distraction, dependence, multitasking, time spent calling, time spent using social networking sites and perception on the effect of MPUB on SAP) considered. It further revealed that students' hours of study per day explains more of the variations in SAP than their MPUB. More so, none of the MPUB variables individually meets the minimum consistency score of .85, indicating that no single MPUB variable is by itself sufficient to influence SAP. However, implementing the MPUB variables as a configuration reveals that there are three pathways to attaining high academic achievements. The major finding of the present study suggests that combining several MPUB variables may be more effective than focusing on individual MPUB variables when investigating the relationship between SAP and their MPUB.
A Study on the Chain Ratio-Type Estimator of Finite Population Variance, Feb 24, 2014
We suggest an estimator using two auxiliary variables for the estimation of the unknown populatio... more We suggest an estimator using two auxiliary variables for the estimation of the unknown population variance. The bias and the
mean square error of the proposed estimator are obtained to the first order of approximations. In addition, the problem is extended
to two-phase sampling scheme. After theoretical comparisons, as an illustration, a numerical comparison is carried out to examine
the performance of the suggested estimator with several estimators.
In this paper, we suggest an estimator of the population mean of the variable of interest y in th... more In this paper, we suggest an estimator of the population mean of the variable of interest y in the presence of non-response using exponential estimator in two situations. We obtain expressions for the bias, mean square error, and optimum values of n and g (the inverse sampling rate) for the suggested estimators. The performance of the suggested estimator is compared theoretically and numerically with the Hansen and Hurwitz, Cochran and Rao estimators. Both numerical and theoretical results are encouraging.
The properties of stratifi ed sampling can diff er considerably by using systematic sampling in e... more The properties of stratifi ed sampling can diff er considerably by using systematic sampling in each stratum, as opposed to the commonly used simple random sampling within strata. Several authors have worked on stratifi ed sampling using simple random sampling; this is known as stratifi ed simple random sampling with relatively little attention given to systematic sampling. This research is concerned with the development, analysis and implementation of a diff erent class of stratifi ed sampling called stratifi ed systematic sampling. We investigated proposed estimation method under two methods of allocation of units within stratum and tested its performance with the existing method in three populations using the standard error, coeff icient of variation and design eff ect. We also examined the gain and relative gain in precision of the design technique considered coupled with the eff iciency of the proposed estimation methods with the existing methods in terms of variance ratio. The results of the analysis revealed that the proposed estimation methods irrespective of any methods of allocations is more precise and eff icient than the existing methods and the Neyman stratifi ed systematic sampling performed the best in gaining variance reduction in all three sets of data.
Most literatures on daily water intake are focused on developed countries and to our knowledge; t... more Most literatures on daily water intake are focused on developed countries and to our knowledge; there is limited information on the hydration status of Nigerians. Our objective was to describe daily water intake (DWI) among Nigerian students, develop a model for the prediction of students' DWI and examine the association between DWI and four predictor variables. Data on DWI for 150 students aged 18-26 years were collected through a survey conducted at Kwara State University in February, 2013 together with information on their age, weight, gender and awareness of dieticians' recommendation. Our results indicates that students' DWI varies by gender with male students drinking more than their female counterparts; although, the awareness rate is higher in females than males. We found that nearly half of participants (44%) drank less than 2.7 L of water/day, 25% between 2.7 and 3.7 L/day and 31% reported drinking more than 3.7 L of water/day. Results also revealed that students' DWI decline with age but increases with weight and one-intwo of the students are unaware of the dangers of poor hydration. Arguably, this study is the first description of DWI among Nigerian students and fills the gap in the literature by developing two models for the prediction of students' DWI. In light of the significance of the knowledge and awareness of Dieticians' recommendation on DWI (as evidence in this study) and the low awareness rate existing among the students; nutrition and health promotion program on the benefits of adequate DWI by schools and health organizations is extremely important. This has the potential of improving the health of students.
Preface: 4 1. Use of auxiliary information for estimating population mean in systematic sampling ... more Preface: 4 1. Use of auxiliary information for estimating population mean in systematic sampling under non-response: 5 2. Some improved estimators of population mean using information on two auxiliary attributes: 17 3. Study of some improved ratio type estimators under second order approximation: 25
New estimators for estimating the finite population mean using two auxiliary variables under simp... more New estimators for estimating the finite population mean using two auxiliary variables under simple and stratified sampling design is proposed. Their properties (e.g., mean square error) are studied to the first order of approximation. More so, some estimators are shown to be a particular member of this estimator. Furthermore, comparison of the proposed estimator with the usual unbiased estimator and other estimators considered in this paper reveals interesting results. These results are further supported with an empirical study using four natural data from literature.
Most literatures on daily water intake are focused on developed countries and to our knowledge; t... more Most literatures on daily water intake are focused on developed countries and to our knowledge; there is limited information on the hydration status of Nigerians. Our objective was to describe daily water intake (DWI) among Nigerian students, develop a model for the prediction of students' DWI and examine the association between DWI and four predictor variables. Data on DWI for 150 students aged 18-26 years were collected through a survey conducted at Kwara State University in February, 2013 together with information on their age, weight, gender and awareness of dieticians' recommendation. Our results indicates that students' DWI varies by gender with male students drinking more than their female counterparts; although, the awareness rate is higher in females than males. We found that nearly half of participants (44%) drank less than 2.7 L of water/day, 25% between 2.7 and 3.7 L/day and 31% reported drinking more than 3.7 L of water/day. Results also revealed that students' DWI decline with age but increases with weight and one-intwo of the students are unaware of the dangers of poor hydration. Arguably, this study is the first description of DWI among Nigerian students and fills the gap in the literature by developing two models for the prediction of students' DWI. In light of the significance of the knowledge and awareness of Dieticians' recommendation on DWI (as evidence in this study) and the low awareness rate existing among the students; nutrition and health promotion program on the benefits of adequate DWI by schools and health organizations is extremely important. This has the potential of improving the health of students.
One of the key issues plaguing the existing studies on the use of the social networking sites (SN... more One of the key issues plaguing the existing studies on the use of the social networking sites (SNSs) is the lack of a uniform index for measuring the time spent on the sites. The present investigation tries to fill this gap by conceptualizing, developing, and validating a new construct, which we referred to as social networking time use scale (SONTUS). To achieve this, two separate studies were conducted. The data for the first study was collected from 2049 individuals through quota sampling approach. Meanwhile, in this first study, we used exploratory factor analysis to identify the dimension of the SONTUS construct. Findings from this study reveal that SONTUS has five factors with good measurement properties. The main aim of the second study (where we utilized data from 1808 people) is to carry out a confirmatory factor analysis (CFA) and tests three hypothesized models. In addition, it aims to investigate the construct validity of SONTUS; and to achieve this, we used 10 personality and well-being measures, and two theoretically related constructs to SONTUS. The CFA results showed that SONTUS has five factor solution consisting of 29 items and that the model with 5 first-order factors with 1 second-order factor is the most suitable model for the study population. Additionally, the second study provides preliminary evidence for the convergent, predictive, and incremental validity of SONTUS. Overall, the findings from our exploratory (study 1) and confirmatory (study 2) studies shows that SONTUS can be used as a standardized instrument for measuring time spent on sites.
With the growing amount of research on the use of technology, especially the mobile phones, the p... more With the growing amount of research on the use of technology, especially the mobile phones, the paucity of research in the area of mobile phone use that focus on the reasons why students use their mobile phones during lecture periods is somewhat surprising. Findings from the previous studies have documented that students continue to use their mobile phones during lecture periods even in classes where its use is banned. Thus, the motives that determine students' continued intention to use their mobile phones during lecture periods becomes an important issue that deserves urgent attention from researchers and education policymakers. In the present investigation, we tried to fill this gap by examining the determinants of students' continuance use of mobile phones during lecture periods. To achieve this, three stages of instrument development (item generation, scale development, and instrument testing) were undertaken through two studies. The results of the exploratory and confirmatory factor analysis confirmed the existence of six dimensions in the proposed measurement instrument (which we referred to as gravitating towards mobile phone (GoToMP)); the dimensions are boredom, class-related use, social connection, emergency, addiction, and perceived behavioral control. The combined findings from the two studies reported here provide initial evidence that GoToMP exhibits excellent psychometric properties and can be used in future empirical research on mobile phone use behaviors of students.
We addressed two shortcomings in the existing studies that focused on the association between stu... more We addressed two shortcomings in the existing studies that focused on the association between students' academic performance (SAP) and their mobile phone use behaviors (MPUB) in this study by conducting a self-report, student-based cross-sectional study in two Nigerian universities between February and March 2014. We collected the data for the study from 286 students in the two universities using a convenience-based sampling approach. The data were analyzed using fsQCA version 2.0 and hierarchical linear (blocked) regression (HLR). The HLR results reveal that time spent calling on phone was the only significant predictor of SAP out of the seven MPUB variables (addiction, distraction, dependence, multitasking, time spent calling, time spent using social networking sites and perception on the effect of MPUB on SAP) considered. It further revealed that students' hours of study per day explains more of the variations in SAP than their MPUB. More so, none of the MPUB variables individually meets the minimum consistency score of .85, indicating that no single MPUB variable is by itself sufficient to influence SAP. However, implementing the MPUB variables as a configuration reveals that there are three pathways to attaining high academic achievements. The major finding of the present study suggests that combining several MPUB variables may be more effective than focusing on individual MPUB variables when investigating the relationship between SAP and their MPUB.
A Study on the Chain Ratio-Type Estimator of Finite Population Variance, Feb 24, 2014
We suggest an estimator using two auxiliary variables for the estimation of the unknown populatio... more We suggest an estimator using two auxiliary variables for the estimation of the unknown population variance. The bias and the
mean square error of the proposed estimator are obtained to the first order of approximations. In addition, the problem is extended
to two-phase sampling scheme. After theoretical comparisons, as an illustration, a numerical comparison is carried out to examine
the performance of the suggested estimator with several estimators.
In this paper, we suggest an estimator of the population mean of the variable of interest y in th... more In this paper, we suggest an estimator of the population mean of the variable of interest y in the presence of non-response using exponential estimator in two situations. We obtain expressions for the bias, mean square error, and optimum values of n and g (the inverse sampling rate) for the suggested estimators. The performance of the suggested estimator is compared theoretically and numerically with the Hansen and Hurwitz, Cochran and Rao estimators. Both numerical and theoretical results are encouraging.
The properties of stratifi ed sampling can diff er considerably by using systematic sampling in e... more The properties of stratifi ed sampling can diff er considerably by using systematic sampling in each stratum, as opposed to the commonly used simple random sampling within strata. Several authors have worked on stratifi ed sampling using simple random sampling; this is known as stratifi ed simple random sampling with relatively little attention given to systematic sampling. This research is concerned with the development, analysis and implementation of a diff erent class of stratifi ed sampling called stratifi ed systematic sampling. We investigated proposed estimation method under two methods of allocation of units within stratum and tested its performance with the existing method in three populations using the standard error, coeff icient of variation and design eff ect. We also examined the gain and relative gain in precision of the design technique considered coupled with the eff iciency of the proposed estimation methods with the existing methods in terms of variance ratio. The results of the analysis revealed that the proposed estimation methods irrespective of any methods of allocations is more precise and eff icient than the existing methods and the Neyman stratifi ed systematic sampling performed the best in gaining variance reduction in all three sets of data.
Most literatures on daily water intake are focused on developed countries and to our knowledge; t... more Most literatures on daily water intake are focused on developed countries and to our knowledge; there is limited information on the hydration status of Nigerians. Our objective was to describe daily water intake (DWI) among Nigerian students, develop a model for the prediction of students' DWI and examine the association between DWI and four predictor variables. Data on DWI for 150 students aged 18-26 years were collected through a survey conducted at Kwara State University in February, 2013 together with information on their age, weight, gender and awareness of dieticians' recommendation. Our results indicates that students' DWI varies by gender with male students drinking more than their female counterparts; although, the awareness rate is higher in females than males. We found that nearly half of participants (44%) drank less than 2.7 L of water/day, 25% between 2.7 and 3.7 L/day and 31% reported drinking more than 3.7 L of water/day. Results also revealed that students' DWI decline with age but increases with weight and one-intwo of the students are unaware of the dangers of poor hydration. Arguably, this study is the first description of DWI among Nigerian students and fills the gap in the literature by developing two models for the prediction of students' DWI. In light of the significance of the knowledge and awareness of Dieticians' recommendation on DWI (as evidence in this study) and the low awareness rate existing among the students; nutrition and health promotion program on the benefits of adequate DWI by schools and health organizations is extremely important. This has the potential of improving the health of students.
Preface: 4 1. Use of auxiliary information for estimating population mean in systematic sampling ... more Preface: 4 1. Use of auxiliary information for estimating population mean in systematic sampling under non-response: 5 2. Some improved estimators of population mean using information on two auxiliary attributes: 17 3. Study of some improved ratio type estimators under second order approximation: 25
New estimators for estimating the finite population mean using two auxiliary variables under simp... more New estimators for estimating the finite population mean using two auxiliary variables under simple and stratified sampling design is proposed. Their properties (e.g., mean square error) are studied to the first order of approximation. More so, some estimators are shown to be a particular member of this estimator. Furthermore, comparison of the proposed estimator with the usual unbiased estimator and other estimators considered in this paper reveals interesting results. These results are further supported with an empirical study using four natural data from literature.
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Papers by Yunusa Olufadi
investigation tries to fill this gap by conceptualizing, developing, and validating a new construct, which we referred to as social networking time use scale (SONTUS). To achieve this, two separate studies were conducted. The data for the first study was collected from 2049 individuals through quota sampling approach. Meanwhile, in this first study, we used exploratory factor analysis to identify the dimension of the SONTUS construct. Findings from this study reveal that SONTUS has five factors with good measurement properties. The main aim of the second study (where we utilized data from 1808 people) is to carry out a confirmatory factor analysis (CFA) and tests three hypothesized models. In addition, it aims to investigate the construct validity of SONTUS; and to achieve this, we used 10 personality and well-being measures, and two theoretically related constructs to SONTUS. The CFA results showed that SONTUS has five factor solution consisting of 29 items and that the model with 5 first-order factors with 1 second-order factor is the most suitable model for the study population. Additionally, the second study provides preliminary evidence for the convergent, predictive, and incremental validity of SONTUS. Overall, the findings from our exploratory (study 1) and confirmatory (study 2) studies shows that SONTUS can be used as a standardized instrument for measuring time spent on sites.
mean square error of the proposed estimator are obtained to the first order of approximations. In addition, the problem is extended
to two-phase sampling scheme. After theoretical comparisons, as an illustration, a numerical comparison is carried out to examine
the performance of the suggested estimator with several estimators.
investigation tries to fill this gap by conceptualizing, developing, and validating a new construct, which we referred to as social networking time use scale (SONTUS). To achieve this, two separate studies were conducted. The data for the first study was collected from 2049 individuals through quota sampling approach. Meanwhile, in this first study, we used exploratory factor analysis to identify the dimension of the SONTUS construct. Findings from this study reveal that SONTUS has five factors with good measurement properties. The main aim of the second study (where we utilized data from 1808 people) is to carry out a confirmatory factor analysis (CFA) and tests three hypothesized models. In addition, it aims to investigate the construct validity of SONTUS; and to achieve this, we used 10 personality and well-being measures, and two theoretically related constructs to SONTUS. The CFA results showed that SONTUS has five factor solution consisting of 29 items and that the model with 5 first-order factors with 1 second-order factor is the most suitable model for the study population. Additionally, the second study provides preliminary evidence for the convergent, predictive, and incremental validity of SONTUS. Overall, the findings from our exploratory (study 1) and confirmatory (study 2) studies shows that SONTUS can be used as a standardized instrument for measuring time spent on sites.
mean square error of the proposed estimator are obtained to the first order of approximations. In addition, the problem is extended
to two-phase sampling scheme. After theoretical comparisons, as an illustration, a numerical comparison is carried out to examine
the performance of the suggested estimator with several estimators.