So if we have. The x and y-axis, here we have the time. And here we have the cost or the units produced, and as I mentioned, we do have kind of an S-curve. Let's do the following, approximately. So this is around a curve of an S-curve of a specific work package. We mentioned that the end of the cost of the work package, we referred to that as the budgeted costs at completion. And we mentioned that there is a study date at any given time during the cost you have allocated for a work package. Let's say we want to study here T, or that we can refer to as the study date. We can at any given time on the duration of the work package. The units that are indicated by the S-curve itself or the base line or the budgeted curve are called budgeted cost of work scheduled. So let's say we have here the study date, the intersection here is the budgeted costs of work scheduled. At the field, there is a tracking system to report or provide information on the actual costs of work performed, or what we refer to as ACWP. And also, we have the end value which is the budgeted costs of work performed, the percentage times the budget cost at completion. So, we have the ACWP and that BCWP also can vary in the line here when studying. So the ACWB could be here, could be here, could be here, here, here. And the BCWP, the end value, also it could be anywhere also on the line. The relationship between the ACWP and the BC CWP. And the BCWS and all these four parameters will get us more understanding, about the schedule and the cost status of our work package or our project in general. And we will talk about this in more details in a few minutes. In summary, the mean four parameters we need to know to understand the foundation of the EVM are the following four. The BCAC, each work package has an initial budget, this is identified or defined as the budgeted cost at completion, BCAC. As for that BCWS, the budgeted dollars or work hours to date at the study date as I just draw at the T, the study date, represent what you planned to do. This is called budgeted cost of work scheduled, BCWS. Now the ACWP is the actual dollars or working hours to the study date, represent what you have paid for. This is measured in the field, and called the actual cost of worked performed ACWP. Finally, BCWP which is the earned value. And it is the measured dollars or work hours to date represent what you did. And, it is equal to the percent complete times the BCAC, the first parameter here. Which is called budgeted cost of work performed or BCWP. Now the level of expected production as I just mentioned is shown as an S-curve that we refer to, as I mention, the baseline or the budgeted curve. And we can see it here, and T is the study date. And BCAC, the first parameter here, when you complete the S-curve towards the end it will give you the accumulated one, the last number. Any point on the curve here when you have any point that you want to do the study date is parameter number two, the BCWS, budget cost of work scheduled. And that ACWP, the actual one, and the earned value one it could be anywhere on the study date either below, above the curve. And it has a lot of combinations. So speaking of that it is important to know that schedule and cost objectives are being achieved. How we track cost and schedule, and how we characterize them in our project, will be as following. There is two factors or points that I want to refer to here. From a cost status point of view, there is something what we call a cost variance. And it links both the earned value, BCWP, to the actual cost of work performed. The differences between both of them is the variance for the cost. When you divide them, BCWP or the earned value, divided by the ACWP, you get you an performance index for the cost. So a cost performance index, CPI, sometimes some books refers to as CI. Now if the cost variance or the cost index they are positive, or greater than one, this means that earned value is more than the actual cost before performed. That will give you a conclusion that the accounts of the project or that account you are studying is within budget. But if, and that's, I highlighted here one sentence, that means, less is being paid in the field than was originally budgeted for. The other way around if the earned value minus the actual cost for perform is negative or less than one, in the reference to the cost index. That's mean the accounts is overrunning the budget. The actual cost is greater than the cost budgeted. The schedule has similar approach to the cost status and the earned value method, and it has also variance and then index. That schedule variance connects also the earned value, the BCWP to the budgeted cost of workers scheduled. Which is identified on the S-curve before you reach to the top of the budget cost at completion. So any point there is the budgeted cost of work scheduled. So the relation between this and the earned value on that study date, it give you the schedule variance. And when you divide them both, similar concept to what we did here in the cost index and the cost variance, the schedule performance index or schedule index is equal to the earned value, the BCWP, divided by the budgeted cost of works schedule. Again, if the variance and the index for the schedule is positive and above one, then accounts are ahead of schedule. And if the schedule variance and schedule performance index is less than one and variance is negative, then accounts are behind the schedule. So if you want to look at the cost and the schedule variance you can use either the variance or the index, or you can use both. Here to learn it in our module, in our course I'm using both so as you have an idea if you heard both terms to know exactly what's going on. And a positive variance, this is kind of a quick summary of this slide. A positive variance and an index of one or greater is a favorable performance.
