(1) In considering whether a bargaining unit is appropriate, the board shall consider such factors as:

(a) similarity of duties;

(b) licensure;

(c) conditions of employment;

(d) community of interest;

(e) wages;

(f) hours;

(g) fringe benefits and other working conditions;

(h) the history of collective bargaining;

(i) common supervision;

(j) common personnel policies;

(k) extent of integration of work functions and interchange among employees affected; and,

(l) desires of the employees.