The effect of sex education on adolescents' use of condoms: applying the Solomon four-group design

Health Educ Q. 1996 Feb;23(1):34-47. doi: 10.1177/109019819602300103.


A school-based sex education program was developed in order to prevent sexually transmitted diseases and unwanted pregnancies. A Solomon four-group design, with random assignment to the different conditions, was used to evaluate an intervention based on cognitive social learning theory and social influence theory. The main goal of the intervention was to increase use of condoms. A stratified sample of 124 classes (2,411 students) was drawn at random from all the upper secondary schools (high schools/colleges) in one county in Norway. The results indicate a consistent interaction between pretest and intervention, which seems to have an effect on condom use. Pretest or intervention alone did not contribute to this effect. The interaction effect appeared among the students with few sexual partners. Several possible explanations to the observed interaction effect and the implication for future interventions are discussed.

PIP: This study involved the testing of a school-based sex education program in Norway which sought to prevent sexually transmitted diseases (STDs) and unwanted pregnancies by achieving an increased use of condoms. The intervention was based on cognitive social learning theory and social influence theory and was evaluated using a Solomon four-group design. The intervention involved the training of peer educators who spent two classroom days 1) identifying facts, 2) identifying situations and behavior that increased the risk of acquiring a STD or becoming pregnant, and 3) identifying the reasons why young people fail to use contraceptives and generating solutions that could be realized immediately. The peer educators developed the content of the education conveyed to younger peers (who were not studied). The random stratified sample contained 124 classes (2411 students). Of the 30 classes randomly assigned to receive the intervention, 15 classes answered the pretest questionnaire. Of the 94 control classes, 47 received the pretest. All classes were given two post-test questionnaires, one at six months and one at a year after the intervention. Individuals were used as the units of logistic regression analyses with the use of condoms as the dependent variable. The most important finding was the consistent interaction between the intervention and the pretest that seemed to have an effect on condom use. The intervention itself had no direct effect on behavior. The implications of these findings are that repetition is important in order to reach students at their most receptive period. This study also underscored the importance of using the Solomon four-group design which provides a control for the possible effect of interactions such as that observed between the pretest and the intervention.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Condoms / statistics & numerical data*
  • Curriculum
  • Data Interpretation, Statistical
  • Female
  • Health Knowledge, Attitudes, Practice*
  • Humans
  • Male
  • Norway
  • Pregnancy
  • Pregnancy in Adolescence
  • Sex Education*
  • Sexually Transmitted Diseases / prevention & control