Surface height measurement method using dummy disk

A method, comprising

• making a polishing table and a dummy disk rotate;
• bringing the dummy disk into contact with a table surface of the polishing table while a liquid is supplied to the table surface;
• measuring heights of the table surface at a plurality of measurement points while the dummy disk is moved on the table surface;
• and
• creating a table profile showing tilt of the table surface from measurement values of the heights of the table surface,
• wherein the dummy disk is fixed to a disk holder of a dresser when heights of a table surface of a polishing table are measured,
• the dummy disk comprises:
• a first surface capable of coming into contact with the disk holder;
• and
• a second surface which is on an opposite side of the first surface,
• wherein the second surface has a plurality of liquid discharge channels, and
• the plurality of liquid discharge channels extends from one end of the second surface to the other end.