  Visual photometry, the estimation of stellar brightness by eye, continues to
provide valuable data even in this highly-instrumented era. However, the
eye-brain system functions differently from electronic sensors and its products
can be expected to have different characteristics. Here I characterize some
aspects of the visual data set by examining ten well-observed variable stars
from the AAVSO database. The standard deviation around a best-fit curve ranges
from 0.14 to 0.34 magnitude, smaller than most previous estimates. The
difference in scatter between stars is significant, but does not correlate with
such things as range or quickness of variation, or even with color. Naked-eye
variables, which would be expected to be more difficult to observe accurately,
in fact show the smallest scatter. The difference between observers (bias) is
less important than each observer's internal precision. A given observer's
precision is not set but varies from star to star for unknown reasons. I note
some results relevant to other citizen science projects.
