Estimation of Variance Using Known Coefficient of Variation and Median of an Auxiliary Variable

A modified ratio type variance estimator for estimating population variance of a study variable when the population median and coefficient of variation of an auxiliary variable are known is proposed. The bias and mean squared error of the proposed estimator are derived and conditions under which the proposed estimator performs better than the traditional ratio type variance estimators and modified ratio type variance estimators are obtained. Using a numerical study results show that the proposed estimator performs better than the traditional ratio type variance estimator and existing modified ratio type variance estimators

Estimation of population mean using co-efficient of variation and median of an auxiliary variable

Abstract The present paper deals with a class of modified rat io estimators for estimation of population mean of the study variable using the linear comb ination of the known values of the Co-efficient of Variation and the Median of the auxiliary variable. The biases and the mean squared errors of the proposed estimators are derived and are compared with that of existing modified ratio estimators. Further we have also derived the conditions for which the proposed estimators perform better than the existing modified rat io estimators. The performances of the proposed estimators are also assessed with that of the existing estimators for certain natural populations. From the numerical study it is observed that the proposed modified ratio estimators perform better than the existing modified rat io estimators

Estimation of population mean using known median and co-efficient of skewness

Abstract The present paper deals with two modified ratio estimators for estimation of population mean of the study variable using the linear co mbination of the known population values of the Median and the Co-efficient of Skewness of the auxiliary variab le. The biases and the mean squared errors of the proposed estimators are derived and are compared with that of existing modified ratio estimators for certain natural populations. Further we have also derived the conditions for which the proposed estimators perform better than the existing mod ified rat io estimators. Fro m the emp irical study it is also observed that the proposed modified ratio estimators perform better than the existing modified ratio estimators

Estimation of Finite Population Mean Using Deciles of an Auxiliary Variable

The present paper deals with a class of modified ratio estimators for estimation of population mean of the study variable when the population deciles of the auxiliary variable are known. The biases and the mean squared errors of the proposed estimators are derived and compared with that of existing modified ratio estimators for certain known populations. Further, we have also derived the conditions for which the proposed estimators perform better than the existing modified ratio estimators. From the numerical study it is also observed that the proposed modified ratio estimators perform better than the existing modified ratio estimators

Not Available

Not AvailableCommercial scale cultivation of Kappaphycus alvarezii, an introduced seaweed species has proved to be a profitable alternate livelihood in Palk Bay, Tamil Nadu, India since 2003. The current study was undertaken to evaluate the decadal changes in water quality during the period of large scale commercial cultivation of K. alvarezii. The hydrographic and water quality parameters were measured following standard procedures across three seasons (southwest monsoon, northeast monsoon and spring inter-monsoon). Consistently significant variations were not observed for the physico-chemical parameters between the culture and control sites in all the three culture locations during the three seasons. The observed variations were mostly site-specific. Statistical analyses revealed that there is no consistent variation of physico-chemical parameters in the study area in relation to the culture, control and reference sites. A comparison of the current study and previously reported aggregate data in this context indicated that the nutrient concentration was significantly higher during the current study than when compared to the pre-culture and initiation stages of culture, indicating no depletion in nutrient content due to seaweed culture. Moreover, long-term changes are insignificant in the Palk Bay region because of the influence of the Bay of Bengal waters seasonally enriched with inorganic nutrients from the major rivers draining into it during monsoon and the transport of nutrients across the coastal waters by the coastal and tidal currents. Therefore, the variations in the physico-chemical properties cannot be directly attributed as an impact of seaweed cultivation in Palk Bay. Rather, the changes were observed to be seasonal and found to be within the range already reported for this part of the coast.Not Availabl