Investigations on fitness of pointing time prediction model

The authors previously found that the index of difficulty (ID) definition in Fitts´ model might not consistently capture actual pointing difficulty among target design variations. In this paper, the authors first evaluate the applicability of possible models other than Fitts´ one. Multiple regression models are found to be able to appropriately represent the effects of target design variations. The authors next make an attempt to improve the definition of ID in Fitts´ model. Our idea is to raise the size or the distance values depending on the screen size. The modified model is found to fit well to the users´ pointing data.