Browsing by Author "Dawodu, O. O."

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    Comparison of Some Sample Selection Procedures In Probability Proportional to Size
    (ICASTOR Journal of Engineering, 2016) Dawodu, O. O.; Adewara, A. A.
    The importance of probability proportional to size sampling cannot be over emphasized. In recent times, Statisticians often work on complex survey data which involve weighting, as a result of the unequal probability nature of units. There is need to work on design weights, which is defined as the inverse of the probability of inclusion of single unit in the sample. Two simulated data sets are generated using ܴin order to obtain the probability of inclusion of single unit and also the joint probability of inclusion of units in the sample. Auxiliary variables and variables of interest were generated in such a way that there exists reasonable correlation between both. A procedure for selecting samples with probability proportional to size nature without replacement was proposed. This procedure could be used with Horvitz and Thompson estimator of variance. The variance estimates are obtained using the modified sample selection procedure and an existing procedure, and results obtained. For the two data sets, it is observed that the modified procedure is more efficient than the existing one.
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    Efficiency of Alodat Sample Selection Procedure over Sen - Midzuno and Yates - Grundy Draw by Draw under Unequal Probability Sampling without Replacement Sample Size 2
    (Journal of Mathematics Research, 2011) Dawodu, O. O.; Adewara, A. A.; Olayiwola, O. M.
    This paper compare the efficiency of Alodat sample selection procedure over Sen - Midzuno and Yates - Grundy draw by draw using Yates - Grundy estimator under unequal probability sampling without replacement sample size 2, carried out using the data from the 2008 Demographic and health survey in Nigeria. We studied the distribution of pregnant women age 15 - 49, and children under age five in Nigeria, who use mosquito nets as a means of preventing malaria. These data sets are: (1) the number of pregnant women age 15 - 49 who slept under mosquito nets the night before the survey, and (2) the number of children under age five who slept under mosquito nets the night before the survey. (1) and (2) above are the variables of interest. The data were collected based on the six geo-political zones in Nigeria [i.e. South South, South West, South East, North West, North East, North Central]. The auxiliary variable is the number of Local Government in each geo-political zone in Nigeria. The Yates - Grundy estimate obtained using Alodat sample selection is more efficient than using Sen - Midzuno and Yates - Grundy selection procedures.
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    Rao, Hartley, and Cochran’s Sampling Scheme: Application
    (Mathematical Theory and Modeling, 2013) Dawodu, O. O.; Adewara, A. A.; Oshungade, I. O.
    This paper takes a look at the Rao, Hartley, and Cochran’s sampling scheme, when it is required to select sample of sizes 4, 6, 12, and 18 with probability proportional to size without replacement sampling (unequal probability sampling without replacement). This is done by using the data from the 2008 Nigeria Demographic and Health Survey (NDHS). We studied the distribution of women age 15 – 49 years employed in the 12 months preceding the survey by type of employer. Here, we considered self-employed women alone. It is shown how sample of sizes 4, 6, 12, and 18 could be randomly selected from the population of size 36. Population total and variance were computed with confidence interval constructed for the population total. For the randomly selected states in this paper, we realized that as the sample size increases, the variance and standard error decreases.
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    RELATIVE EFFICIENCY OF TWO SAMPLE SELECTION PROCEDURES IN PROBABILITY PROPORTIONAL TO SIZE SAMPLING WITHOUT REPLACEMENT
    (Jour. of Mathematical Science, 2017) Dawodu, O. O.; Adewara, A. A.
    In probability proportional to size sampling, units have unequal chances of being selected. It is necessary to consider the unequal probability nature of units. It is important to compare the relative efficiency of a complex design with that of a simple design, so as to know if there would be any gain or loss in efficiency. Here, two sample selection procedures in probability proportional to size sampling without replacement are considered as complex designs. They are: Dawodu and Adewara, and Basit and Shahbaz procedures. Simple random sampling without replacement is used here, as a simple design. The complex sample designs are compared with the simple one. Results are compared with simple random sampling without replacement, in order to get the relative efficiency. It was found that, for this dataset, there was more gain in efficiency when Dawodu and Adewara procedure was used, than when Basit and Shahbaz procedure was used.