I'm sure most of the responses to your comment have technical reasons for their disagreement, but I agree with you for anecdotal reasons. I have a Garmin GPS I

I'm sure most of the responses to your comment have technical reasons for their disagreement, but I agree with you for anecdotal reasons. I have a Garmin GPS I wear when I run, it connects to 3 (at least?) satellites and I've never seen it be off by more than a few feet in altitude. I'm sure there are some random points in the graph with anomalous readings but the overall "smoothed" graph seems very accurate. Granted, there are times it loses its signal altogether, but that is not a resolution issue.