EXHIBIT 11 BARRETT BUSINESS SERVICES, INC. STATEMENT OF CALCULATION OF BASIC AND DILUTED COMMON SHARES OUTSTANDING Three Months Ended June 30, 2002 ----------------------- Weighted average number of basic shares outstanding 5,806,021 Stock option plan shares to be issued at prices ranging from $1.45 to $17.75 per share 248,365 Less: Assumed purchase at average market price during the period using proceeds received upon exercise of options and purchase of stock, and using tax benefits of compensation due to premature dispositions (228,164) ----------------------- Weighted average number of diluted shares outstanding 5,826,222 -----------------------