The PANSS assesses the severity of schizophrenia symptoms through a 30-item clinician-rated inventory organized into a positive subscale (7 items), a negative subscale (7 items) and a general psychopathology subscale (16 items). For each item, symptoms are rated on a 7-point scale from 1 (absent) to 7 (extreme). The PANSS total score for each participant was calculated as the sum of the rating assigned to each of the 30 PANSS items, and ranges from 30 (lowest total score) to 210 (highest total score). Higher and lower change scores reflect symptom worsening and improvement, respectively. Risperidone and placebo were active and inactive controls, respectively.

All participants who receive ≥1 dose of MK-8189 (16 mg or 24 mg), risperidone, or placebo, and have both a baseline measurement and ≥1 valid post-baseline assessment, are included. Per protocol, the effect of the 8 mg dose was not assessed.

An AE is any untoward medical occurrence in a clinical study participant, temporarily associated with the use of study intervention, whether or not considered related to the study intervention. Per protocol, events were assessed for the first 6 weeks of treatment.

All participants who received ≥1 dose of study intervention are included.

The PANSS Positive Subscale (PSS) assesses the severity of schizophrenia symptoms. The PANSS PSS score was calculated as the sum of the rating assigned to each of the 7 PSS items and ranges from 7 (lowest total score) to 49 (highest total score). Higher and lower change scores reflect symptom worsening and improvement, respectively. Risperidone and placebo were active and inactive controls, respectively.

All participants who received ≥1 dose of MK-8189 (16 mg or 24 mg), risperidone, or placebo, and have both a baseline measurement and ≥1 valid post-baseline assessment, are included. Per protocol, the effect of the 8 mg dose was not assessed.

The CGI-S is a single item 7-point clinician rated scale for assessing the global severity of the participant's illness. CGI-S scores range from 1 (participant normal, not ill) to 7 (participant extremely ill); higher and lower change from baseline scores indicate symptom worsening and improvement, respectively. Risperidone and placebo were active and inactive controls, respectively.

All participants who received ≥1 dose of MK-8189 (16 mg or 24 mg), risperidone, or placebo, and have both a baseline measurement and ≥1 valid post-baseline assessment, are included. Per protocol, the effect of the 8 mg dose was not assessed.

The change from baseline in body weigh was determined at Week 12. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.

All participants who received ≥1 dose of MK-8189, risperidone, or placebo, and have both a baseline measurement and ≥1 valid post-baseline assessment, are included.

An AE is any untoward medical occurrence in a clinical study participant, temporarily associated with the use of study intervention, whether or not considered related to the study intervention. Per protocol, events were assessed for the first 6 weeks of treatment.

All participants who received ≥1 dose of study intervention are included.

The change from baseline in body weigh was determined at Week 6. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.

All participants who received ≥1 dose of MK-8189, risperidone, or placebo, and have both a baseline measurement and ≥1 valid post-baseline assessment, are included.

The change from baseline in body weigh was determined at Week 12. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.

All participants who received ≥1 dose of MK-8189 (16 or 24 mg), risperidone, or placebo, and have both a baseline measurement and ≥1 valid post-baseline assessment, are included. Per protocol, the 8 mg arm was excluded from analysis.

The change from baseline in body weigh was determined at Week 6. Negative and positive values represent body weight loss and gain from baseline, respectively. Weight was measured using a standardized scale. Risperidone and placebo were active and inactive controls, respectively.

All participants who received ≥1 dose of MK-8189 (16 or 24 mg), risperidone, or placebo, and have both a baseline measurement and ≥1 valid post-baseline assessment, are included. Per protocol, the 8 mg arm was excluded from analysis.