In grad school, I took a GPS class. We had learned about different GPS devices and their varying accuracies, and I wanted to test what my phone could do with only what was native to the device.

At the Nichols Arboretum in Ann Arbor, there are 27 square flower beds. Using my phone and Survey123, I marked the corners of each flower bed and created a polygon layer of 27 "squares." I then used satellite imagery to manually digitize the beds. I rasterized the two polygon layers and and calculated the overall accuracy and Kappa values. The Overall Accuracy was 56.158%, and the Kappa was 40.972% for individual plots. These results showed how the iPhone's native GPS may be good enough to navigate around town, but it's nowhere near accurate enough for research.