A tool that quantifies the discrepancy between observed data and values predicted by a model, often in regression analysis. The device computes the sum of the squares of the differences between actual and predicted values. For instance, if a regression model predicts a house price of $300,000, but the actual price is $320,000, the squared residual is $400,000,000. The calculator repeats this process for each data point and sums the results.
This calculation is fundamental in assessing the goodness-of-fit of a statistical model. A lower value generally indicates a better fit, suggesting that the model accurately describes the data. It also plays a crucial role in comparing different models; the model with the lower value is often preferred. Historically, the manual calculation of this metric was a time-consuming process, but the advent of electronic calculators and statistical software has streamlined its computation and increased its accessibility.