Abstract: Based upon an analysis of the relationship between patrameters of the weight function of the negative power form and the capability of locating blunders, it is found necessery to handle separately the choice of the basic variable of the weight function and the test value for statistical tests. The result of investigation shows that the so-called "enlarged residual" should be used as the basic variable of the weight function for the first two iterations, and it is better to choose the residual itself for the following. The "Standardized residual" is used as the statistical test value, while the power value of the weight function is taken from - 2.5 to - 4.0.