Polling customers. An online store chooses an SRS of 100 customers from its list of all people who have bought something from them in the last year. It asks those selected how satisfied they are with the store’s Web site. If it selected two SRSs of 100 customers at the same time, the two samples would give somewhat different results. Is this variation a source of sampling error or of nonsampling error? Would the survey’s announced margin of error take this source of error into account?

AppendixLO1