The present investigation is dealing with the variances of five long staple Egyptian cotton (Gossypium barbadense L.) genotypes, with respect to yield, its components and fiber properties in an old location (Middle Delta) and a new location (North Delta) during 2004 and 2005 seasons. The final goal is to study the possibility of suggestion a modified analysis of randomized complete block design to replace the use of combined analysis. The five genotypes were cultivars, viz. G.85, G.86 and G.89, the others were hybrids, viz (G.89 x G.86) and (G.89 x Pima S-6). Modified analysis depends on the use of the five genotypes twice, however the number of the replicated genotypes remains the same. The modified analysis gave equal results as the traditional combined. In addition the modified analysis does not need using the Bartlett test .

An alternative way to estimate the coefficient variance in the Swamy's RCR model has been derived using Minimum Norm Quadratic Estimation (MINQUE), and the Iteration Almost Unbiased Estimator (IAUE) methods. The estimators' performance in the RCR model are examined in Monte Carlo study. The Monte Carlo study provides some insight into how well the RCR model performs in small, medium, and large samples in the case of random, mixed, and fixed coefficient regression. We found that using MINQUE method to estimate the coefficient variance has reduce the probability of having negative variance comparing with the Swamy method. IAUE method was superior, since it gives zero percent of negative 2728 Souha K. Badr et al. variance and has a low variation and a low bias in estimation coefficient parameters, even in case of fixed coefficients.