Tag Archives: Skewness

On The Comparison of Some Methods of Allocation in Stratified Random Sampling for Skewed Population (Published)

A study to evaluate and compare some methods of allocation in stratified random sampling suitable for the estimation of population total of a skewed population was carried out in this paper. We looked at three methods of allocation in the above scheme namely; Optimum allocation, N-proportional allocation, and variable (X) proportional allocation methods. We investigate the condition under which one method of allocation is better than the other using three sets of real life data on staff and student enrolment, collected from the record of the Teaching Service Commission (TESCOM) Oyo State Nigeria. The third set of data is on Income and expenditure of Industrial and General Insurance (IGI) Plc.   We found out that optimum allocation is the least and the best despite variation observed in the sizes of nh within the strata.  

Keywords: Allocation, Estimation, Sampling, Skewness, Stratification

Characterization of Spatial Variability of Some Physiochemical Soil Properties of Mesopotamian Plain Soils (Published)

The present study is conducted to characterize the spatial variability of some soil physio-chemical properties (sand, silt, clay, pH ,ECe ,CEC ,Esp ,O.M and CaCO3) for selected soil series from Mid-Mesopotamian plain. Five soil series were recognized(MM5,MP5.Dw45,DF97,and DP45).Descriptive statistics were used including(Min., Max., Mean, Standard deviation , coefficient of variation, Skewness and kurtosis) .The results showed that, soils was differing significantly (ρ≤ 0.05) in all studied physio- chemical properties except for and CaCO3.In addition, soils exhibited moderate to high spatial variability in the horizontal scale (cv=21.528-78.327%) in sand and OM respectively except in pH and O.M was of low spatial variability(CV=2.840-8.402%) respectively .Also, soils showed moderate to high vertical spatial variability in their physio-chemical properties ( cv=16.949-88.337%) in sand and clay particles in MP5 and DW45 soil series respectively .On the other hand they showed low and high vertical spatial variability (CV=1.223-102.415%) in pH and O.M of DP45 and MP5 soil series respectively .Accordingly we see that, soil spatial variability must be studied thoroughly for precise soil management and accurate soil sampling system for taking effective management decisions that leads to sustainable agricultural production.

Keywords: Alluvial Soils., Coefficient of Variation, Geomorphic Processes, Pedogenic Process, Skewness, Spatial Variability, Standard Deviation