1. A computer-implemented method for evaluating a total cost of ownership (TCO) of a computing system, the method comprising: receiving a user selection of an area within a TCO measurement model to be in focus for evaluating the TCO of the computing system under evaluation, the TCO measurement model configured for use in determining the TCO of the computing system under evaluation and comprising instances of functional elements, the instances including: an activity element that represents a defined task to be performed in the system; a monitoring task element that represents an observation task to be performed, including collection of data, to determine whether the system functions properly; an analysis task element representing interpretation and decision-making, based at least on the data collected by the observation task; and a frequency element that connects a first one of the functional elements with at least a second functional element selected among the activity element and the monitoring task element, and represents how frequently the first functional element causes the second functional element to be performed; obtaining reference values associated with respective aspects of the selected area of the TCO measurement model, wherein the reference values are obtained using the functional elements while taking into account interdependencies between the frequency element, the first functional element, and the second functional element, and wherein the reference values are associated with a reference TCO of a reference system; obtaining actual values for the computing system under evaluation by: operating the computing system under evaluation; and monitoring the computing system under evaluation during operation, wherein the monitoring obtains the actual values using the functional elements while taking into account interdependencies between the frequency element, the first functional element, and the second functional element; mapping the actual values to the TCO measurement model, the actual values identified as associated with the computing system under evaluation; performing, by a computer system, an analysis to determine the TCO of the computing system under evaluation, wherein the analysis includes comparing the actual values to the reference values according to the mapping and based on the interdependencies between the frequency element, the first functional element, and the second functional element; and recording, by the computer system, a result of the analysis that indicates at least one difference between the TCO of the computing system under evaluation and the reference TCO of the reference system, wherein the result depends on the interdependencies between the frequency element, the first functional element, and the second functional element.