Periodically, software engineers must provide estimates of their effort in developing new software. In the Journal of Empirical Software Engineering (Vol. 9, 2004), multiple regression was used to predict the accuracy of these effort estimates. The dependent variable, defined as the relative error in estimating effort, 

y = (Actual effort - Estimated effort)>(Actual effort)

was determined for each in a sample of n = 49 software development tasks. Two independent variables used in the model for relative error in estimating effort were company role of estimator (x₁ = 1 if developer, 0 if project leader) and previous accuracy (x₂ = 1 if more than 20% accurate, 0 if less than 20% accurate). The multiple regression yielded the prediction equation ŷ = .12 - .28x₁ + .27x₂. The researcher is concerned that the sign of the estimated β multiplied by x₁ is the opposite from what is expected. Give at least one reason why this phenomenon occurred.