On each measure, we determined whether the vendor's score was significantly better than average, not significantly different from average, or significantly worse than average. If a vendor drew 49 or fewer responses in an area, we discarded the results as statistically unstable. This prevented us from rating some smaller vendors.

Reliability Measures

• Problems on arrival (all devices):Based on the percentage of survey respondents who reported one or more problems with the device out of the box.

• Any hardware or software problem (all devices): Based on the percentage of survey respondents who reported any problem at all during the product's lifetime.

• Satisfaction with reliability (all devices):Based on the owner's overall satisfaction with the reliability of the device.