This note describes two studies of the use of a performance modeling tool, CogTool, for making recommendations to improve a user interface. The first study replicates findings by Bonnie John [7]: the rates at which novice modelers made correct recommendations (88.1%) and supported them (68.2%) are close to the values in John's study (91.7% and 75.1%, respectively). A follow-on study of novice modelers on the same task without CogTool produced sig-nificantly lower values. CogTool improves the UI design recommendations made by novices.

In this paper we analyze pointing techniques for simple remote control of nearby and distant objects in an outdoor environment, using a mobile phone. In an experiment we determine the accuracy of pointing at targets from a few meters to a few hundred meters away, either by focusing the phone's camera on a target or holding the phone at waist level in the direction of the target. We describe a simulated network application in which users can activate and control one or more responsive objects using either interaction technique.