Sampling weights are recommended to be incorporated in surveys to compensate for the disproportionality of the sample with respect to the target population of interest. This report presents how to develop sampling weights for a population-based study where a sample was randomly selected and demonstrates the process of developing such sampling weights. We exemplify the development of sampling weights with a real research project entitled School Physical Activity and Nutrition (SPAN) project. In this report, we first introduce the probability-based survey and related key concepts, such as sampling design, sampling frame and sampling weights. Then we discuss the sampling design and the construction of the sampling frame for the SPAN project. We next demonstrate the method and the process of developing the sampling weights for the SPAN project. Lastly, we present the results with an example. / text

This study is unique considering the location (Africa) and the industrial setting (Gold Mining) from which the research was studied as reward systems had mostly been studied in the North-American and European settings. Thus, the study  considered  rewards from the perspective of the African and its natural resource industries such as the gold mining industry.   The methodology employed in the study was based on a case study approach at Golden Star (Bogoso/Prestea) Limited (GSB/PL) with a population size of 1029 employees combining both qualitative and quantitative data obtained through a questionnaire survey of a 278 sample size and structured interview with the Human Resources and Administration Manager. Thus, the method of data collection represents methodological triangulation and the data obtained from the study represents a primary source of data.   The study revealed that all the three generational groups (Baby Boomers, GEN Xers and   GEN Yers) places higher emphasis or priority on financial incentives (high salary and bonuses) over any other incentives when respondents were asked to indicate the reward they prefer most. But when rewards were considered as a total package profile, greater number of  the baby boomers placed more emphasis or priority on packages with highly flexible pension benefits, long term job security and high internal promotions eventhough the salary and bonus components of the packages (profile) were not that attract. The GEN X and GEN Y groups still maintained their reward package profile preferences based on  high financial incentives, training and learning opportunities, personal growth and career advancement.   The study revealed that aside the high preferences for financial incentives such as high salary and bonuses by all the generational groups, few of the  GEN X and GEN Y also exhibited other preferences such as high personal growth, flexible work schedule, attractive company policy and administration, career advancement, working environment, job security and praises and recognition of which the baby boomers did not indicate any preferences or interest.   The study revealed that all the three generational groups (Baby Boomers, GEN X and GEN Y) consider high salary and bonuses as factor which causes employee dissatisfaction when not satisfied or available but when they are satisfied or available also do not motivate or cause satisfaction and thus  confirming Herzberg Two-Factor theory that  factors such as salary or remuneration, job security, working conditions and company policies  only prevent employee dissatisfaction.   The study revealed that all generational groups (baby boomers, GEN X and GEN Y) consider high salaries and bonuses as factor which could lead to lack of satisfaction and motivation of the employee in his current role or position when not available or satisfied and thus this finding confirm the traditional belief that pay is prime, or in some cases the only source of motivation but contradict Herzberg claim that  pay (high salaries and bonuses) is only an extrinsic factor and that when is available or satisfied, pay does not bring satisfaction and motivation but rather prevents dissatisfaction.   The study revealed that GSB/PL rewards systems basically comprises of extrinsic rewards such as high salary levels (pay increases), a bonus scheme,  training  and learning opportunities, job security, Stock options, Retirement/Pension benefits such as social security and provident fund,  promotions,  attractive company policies and administration, praises and recognition, good working environment, flexible work schedule,  Long service awards and benefits such as housing, Health insurance, Vacation/Annual leave benefits, transportation/bussing service, messing (provision of meals to employees only when at work), and educational benefits (for employees dependants).   The study also revealed that the design and implementation of GSB/PL reward systems involves four distinct phases: assessment, design, execution and evaluation phases.   In the end, a suitable conclusion was drawn and a number of recommendations proposed to be implemented by the mining company in safeguarding the interest of both employees and the employer.

Objetivos: Estudar as possibilidades de uso de cadastros de linhas telefônicas residenciais para implementação de inquéritos por amostragem. Descrever presença de vícios potenciais, associados às taxas de coberturas de LTR, nas principais variáveis que usualmente compõem o núcleo de informações de inquéritos epidemiológicos. Métodos: Com base nos dados da Pesquisa Nacional por Amostra de Domicílios (PNAD) no período de 1998 a 2003, exceto 2000, foram estimadas por intervalo de confiança de 95%, as médias e proporções. Nas análises dos dados considerou-se o plano de amostragem complexa. Resultados: No Brasil, houve um crescimento de 50% dos domicílios atendidos por LTR, no período. No entanto, essa evolução não ocorreu de forma uniforme no Brasil. Foram identificados diferentes perfis de usuários de LTR, sendo as principais características relacionadas com a escolaridade, a raça, a posse de um plano de saúde e a localização geográfica. Nas regiões com baixa cobertura de LTR podem ocorrer vícios nas estimativas de prevalências de doenças crônicas. Conclusão: O uso das linhas telefônicas residencias para a realização das entrevistas em inquéritos epidemiológicos mostrou-se viável para as unidades de federação com taxas de cobertura de LTR acima de 70%. / Objectives: To study the possibilities to use sampling frame of telephone interview the implementation of survey sampling. To describe the presence of potential biases associated to with coverage rates of telephone surveys in the main variables that usually compose the information core of epidemiological investigations. Methods: From database of the National Household Sample Survey (PNAD) in the period between 1998 and 2003, except for 2000, the averages and proportions were estimated by a 95% confidence interval. In the statistics analysis , the complex sampling plan was considered. Results: In Brazil, it has been there was a 50% increase in the households served by telephone, during the studied period. However, this evolution did not occur in a uniform way. Different profiles of telephone users were identified, and the main characteristics were related to education, race, the health plans and the geographic location. The regions with low telephone coverage may introduce bias on the estimates of prevalence of chronic diseases. Conclusion: The use of telephone survey for the conduction of interviews during epidemiologic investigations could be suitable to be feasible for the federal units with coverage rates above 70%.

Objetivos: Estudar as possibilidades de uso de cadastros de linhas telefônicas residenciais para implementação de inquéritos por amostragem. Descrever presença de vícios potenciais, associados às taxas de coberturas de LTR, nas principais variáveis que usualmente compõem o núcleo de informações de inquéritos epidemiológicos. Métodos: Com base nos dados da Pesquisa Nacional por Amostra de Domicílios (PNAD) no período de 1998 a 2003, exceto 2000, foram estimadas por intervalo de confiança de 95%, as médias e proporções. Nas análises dos dados considerou-se o plano de amostragem complexa. Resultados: No Brasil, houve um crescimento de 50% dos domicílios atendidos por LTR, no período. No entanto, essa evolução não ocorreu de forma uniforme no Brasil. Foram identificados diferentes perfis de usuários de LTR, sendo as principais características relacionadas com a escolaridade, a raça, a posse de um plano de saúde e a localização geográfica. Nas regiões com baixa cobertura de LTR podem ocorrer vícios nas estimativas de prevalências de doenças crônicas. Conclusão: O uso das linhas telefônicas residencias para a realização das entrevistas em inquéritos epidemiológicos mostrou-se viável para as unidades de federação com taxas de cobertura de LTR acima de 70%. / Objectives: To study the possibilities to use sampling frame of telephone interview the implementation of survey sampling. To describe the presence of potential biases associated to with coverage rates of telephone surveys in the main variables that usually compose the information core of epidemiological investigations. Methods: From database of the National Household Sample Survey (PNAD) in the period between 1998 and 2003, except for 2000, the averages and proportions were estimated by a 95% confidence interval. In the statistics analysis , the complex sampling plan was considered. Results: In Brazil, it has been there was a 50% increase in the households served by telephone, during the studied period. However, this evolution did not occur in a uniform way. Different profiles of telephone users were identified, and the main characteristics were related to education, race, the health plans and the geographic location. The regions with low telephone coverage may introduce bias on the estimates of prevalence of chronic diseases. Conclusion: The use of telephone survey for the conduction of interviews during epidemiologic investigations could be suitable to be feasible for the federal units with coverage rates above 70%.

The objective of this thesis is to investigate the possibility of using machine learn- ing at Statistics Sweden within the Foreign Trade in Services (FTS) statistic, to predict the likelihood of a unit to conduct foreign trade in services. The FTS survey is a sample survey, for which there is no natural frame to sample from. Therefore, prior to sampling a frame is manually constructed each year, starting with a register of all Swedish companies and agencies and in a rule- based manner narrowing it down to contain only what is classified as units likely to trade in services during the year to come. An automatic procedure that would enable reliable predictions is requested. To this end, three different machine learning methods have been analyzed, two rule- based methods (random forest and extreme gradient boosting) and one distance- based method (k nearest neighbors). The models arising from these methods are trained and tested on historically sampled units, for which it is known whether they did trade or not. The results indicate that the two rule-based methods perform well in classifying likely traders. The random forest model is better at finding traders, while the extreme gradient boosting model is better at finding non-traders. The results also indicate interesting patterns when studying different metrics for the models. The results also indicate that when training the rule-based models, the year in which the training data was sampled needs to be taken into account. This entails that cross-validation with random folds should not be used, but rather grouped cross-validation based on year. By including a feature that mirror the state of the economy, the model can adapt its rules to this, meaning that the rules learned on training data can be extended to years beyond training data. Based on the observed results, the final recommendation is to further develop and investigate the performance of the random forest model.