Stress has long been known to influence physical health. Visintainer, Volpicelli, and Seligman (1982) investigated the hypothesis that rats given 60 trials of inescapable shock would be less likely to later reject an implanted tumor than would rats who had received 60 trials of escapable shock or 60 no-shock trials. They obtained the following data:

Inescapable Escapable Shock Shock No Shock Total Reject 8 19 18 45 No Reject 22 11 15 48 Total 30 30 33 93 What would you conclude from these data?