Critical Reasoning: W: The rapid rise in the rate of unemployment is a serious economic problem; it will undoubtedly cost the majority party votes in the coming election. Z: I disagree. Statistics for the past 40 years show that there is no significant relationship between the prevailing level of unemployment and political gains or losses by the party that happens to be in the majority at election time. Which of the following most seriously weakens the force of Z's counterargument?