If the null hypothesis is true you cannot make which kind of error? In reality men drive faster than females. When comparing average driving speed of 10 men and 10 woman, the researcher found men did drive faster (t=1.7, df = 18) No Error No Error + A pharmaceutical company conducts a clinical trial to test a new drug's effectiveness in lowering blood pressure. When comparing the effectiveness of 100 participants after taking the drug, the calculated t-value was 2.59