Initial Number of Additional Centers Use this option to specify the initial number of new centers to be added to increase enrollment rate. The default value is one, assuming that we start adjusting the recruitment rate by adding one new center. To Specify a Value: Either enter the desired value in the text field or move the slider to the right or to the left to change the value. Tip : To change the scale of the slider, right-click on the slider and select Rescale Slider from the pop-up menu. Change the upper or lower boundaries in the that appears, to rescale the slider and click OK .