Instead, evidence regarding the dose equivalency of risperidone and haloperidol has been drawn from less optimal study designs. In the North American trials of Chouinard et al. and Marder and Meibach, as well as in the large multinational trial of Peuskens and colleagues, the researchers randomly assigned patients to different doses of risperidone but used fixed doses of haloperidol (20 mg/day and 10 mg/day, respectively). While these studies indicate that risperidone in the 4–8 mg range was most effective, they provide little data concerning the optimal dose of haloperidol. Other studies containing no risperidone treatment arm, in which patients were randomly assigned to a variety of haloperidol doses, provide mixed results. A study by Van Putten et al. R421559BCECEBAI suggested that 10 and 20 mg of haloperidol were only marginally better than 5 mg and that the 20-mg doses were associated with high levels of side effects. In a trial by Zimbroff and colleagues R421559BCEBAEGD, patients were randomly assigned to three doses of sertindole, three doses of haloperidol, or placebo; for haloperidol, there was a small and nonsignificant advantage for 8 mg/day over 4 mg/day or 16 mg/day.