# Monitoring of Time and Cost Variances of Schedule Using Simple Earned Value Method Indicators
## 2 Materials and Methods: Description of the Scheduled Examined  
Compared to the traditional method of checking the project progress, the EVM method includes the third dimension: earned value, which represents the planned value of the scope of work actually executed, in the assessment of the condition of the project, in addition to planned and actually incurred costs. By developing this method, not only measurement possibilities and assessment of the actual results of operations based on the data found during control periods were obtained, but also analysis of performance trends and forecasts of the future cost of project activities and projections of the final project budget. Appropriate indicators allow at each stage of the implementation of works to assess the current status of the project and the possibility of its implementation within the planned budget and schedule. The indicators used in the EVM method can be calculated for both individual tasks and the entire project, as cumulative earned value [11; 12; 13; 14; 15; 16]. The basis of the earned value method is the Budgeted Cost of Work Performed (BCWP). It shows how much the work done as planned costs. If one wants to calculate it, they should have information on the planned cost of work to be incurred by the date of the inspection, and on the amount of work actually executed to that day. The essence of the earned value method is shown in Figure 1. The curve illustrating the course of BCWS- \"Budgeted Cost of Work Scheduled\" (planned costs) is determined during the project planning phase, its final value is BAC--\"Budget at Completion\" [17]. Curves illustrating the course of BCWP--\"Budgeted Cost of Work Performed\" (earned value) and ACWP--\"Actual Cost of Work Planned\" (costs incurred), are determined during the implementation of the works and can be determined only until the date of inspection. The course of the curves in Figure 1 also allows to see the variances from the budget and the schedule: both on the day of the inspection and forecast values on the day of completing the project. Data from the BCWS, BCWP, and ACWP curves are the basis for calculating further indicators, to which in the EVM method belong: [10]  
* Cost Variance (CV): CV=BCWP--ACWP
* Schedule variance (SV): SV=BCWP--BCWS  
where BCWS--planned cost of the planned work until the day of inspection of the quantity of work of a given task, ACWP--actual cost of the work executed up to the date of inspection of the quantity of work of a given task, BCWP--the planned cost of the work executed to the day of work inspection of this task; value checking how much, according to plan, was paid for the work actually executed. In the study [18], searching for reasons for delayed projects, monotonicity analyzes of the indicator corresponding to these assumptions were carried out, proposing the variance parameter from booked expenditure (AV: Accounting Spending Variance). This indicator is described in the form:  
AV=CV--SVThus, we have  
\[ \begin{split}\text{AV=}&(\text{BCWP}-\text{ACWP})-(\text{BCWP} -\text{BCWS})\text{=}\\ =&\text{BCWP}-\text{ACWP}-\text{BCWP}+\text{BCWS} =\text{BCWS}-\text{ACWP}\end{split}  \tag{4}\]  
The proposed AV parameter monitors financial liquidity, which is the difference between planned and actually incurred costs. In this concept, commonly known as cost management, workflow is defined as \"data and material movement\" through the network of production units. Current control systems, including EVM, focus on analyzing the \"speed\" of cost and time increases, ignoring the problem of the flow of production resources, in which the authors see major failures in their implementation processes. These systems are an effective control tool, but they have one serious limitation, treating each schedule process as an independent activity, the effect of which does not translate into the implementation of subsequent processes.