This paper summarizes the available data on the observation and predic
tion of SEU rates in space. It considers three questions: 1. How good
can a prediction be? 2. How bad can a prediction be? 3. How does the q
uality of the prediction depend on the type of orbit? The paper consid
ers one hundred and twenty-six reports of predicted and observed rates
. These include updated predictions for the CRRES devices. The analysi
s then excludes solar particle events, single event burnout, cases wit
h poor statistics, and cases that are essentially duplicates; leaving
77 comparisons. The heavy ion predictions based on the CREME environme
nts and the proton predictions based on the AP8 environments are both
very successful for their basic environments, but are less accurate fo
r low earth orbits (LEG). The quality of the results depends strongly
on whether the predictions are based on tests with flight parts or wit
h generic parts. The quality also depends on the use of the proper shi
elding around the part. The results appear consistent with suggested m
odifications in these environments based on recent space measurements.
The methods that are used for upset rate predictions appear to be ade
quate for the current generation of devices.