The systematic developments of panel analysis started with the work of Paul Lazarsfeld and his associates. In their published and unpublished papers most of the so-called panel problems have been recognized and tentative solutions have been provided. Examples of panel problems are how to measure change, the occurrence of test-retest effects, panel attrition, regression to the mean, and separating true changes and changes due to unreliability. Present day developments in panel research are compared with these former questions and answers.