In this paper, we investigate the impact of partial channel state information (CSI) on the symbol error rate (SER) in a MIMO broadcast scheduling system. In this scheduling system, each transmit antenna is allocated based on scalar feedback information, which contains the largest effective signal to noise ratio (SNR) value with index for all user terminals. Exact closed-form expressions of the SER for the M-ary QAM and M-ary PSK modulations are presented. Using an asymptotic approach, we quantify the diversity order and SNR gain of the SER for the MIMO broadcast scheduling system employing scalar feedback information. From analysis results, we show insight into how the partial CSI affects the diversity order and SNR gain in the scheduling system. We verify the analytical results through simulation results.