Although the U.S. Bureau of Labor Statistics (BLS) does not provide information specific to the field of global marketing, the BLS did project that the employment of marketing managers will likely grow by about 12% between 2012 and 2022, a rate consistent with the average predicted for all occupations.
Divide the height of the staircase in inches by the intended rise of each step, also in inches, to assist in determining the stair stringer length. The riser height is up to you, though most building codes will not allow a height larger than 7 3/4 inches.
Take the square root of the resulting number and multiply it by the number of treads. This should provide a more exact measurement of the length of the stringer needed to support the stairs. Check building codes in your area to make sure of the maximum riser height and the minimum tread width.