To start off, the monitoring and control phase of "...the project management process consist of the activities involved to observe the process after project implementation, identify problems and risks, and deploy a mitigation strategy to control new processes". Planned value and actual cost matter in both phases because it allows the team to determine budget status and the project's schedule. And this allows the team to determine possible risk in the plan and come up with a strategy to overcome it.

To add on, this will let the team and upper management decide whether or not a project is worth following through on if it hits too many road bumps. If there are major set backs that were not planned for in the planned value and the actual costs begin to skyrocket, its clear that the project will shut down prior to completion.

As we've learned, the planned value (PV) of a project is the estimated cost of the project's activities which have been planned as of the reporting date. On the other hand, the actual value (AV) of the project is how much actual money has been spent on a project on the reporting date. The two numbers are very important to keep track of because as a project manager, you need to try you absolute best to keep the AV on track or under budget, as compared to the PV. This is very important in the monitoring and controlling phase because that is where the project is controlled and kept on schedule and on budget. Otherwise, many projects can become vastly over-budget and may even end up losing the company money if these costs are not supervised.

we can think about the ratio between the two to define the success rate. Planned value is like the target for the team. It is set and defined before the project started as an expectation. However, the Actual cost is how much the team contributed work and how much was able to achieve from that target.

As stated in earlier posts, Planned Value is the expected value (or amount completed) for the project on a certain date, and the Actual Cost is what the project actually ends up costing. These two values matter in the Monitoring & Controlling phase because the are used to calculate Schedule Variance and Cost Variance. The relationships are as follows: Schedule Variance (SV) = Estimated Value (EV) - Planned Value (PV); and Cost Variance (CV) = Estimated Value (EV) - Actual Cost (AC). If the SV is positive, it means that the project is ahead of schedule. If it is negative, then the project is behind schedule. If the CV is positive, then the project is under budget. If it is negative, then the project is over budget. As a project manager, you want to try to maintain a positive SV and CV during the Monitoring and Controlling Phase. If the values are negative, then adjustments should be made.

The various budget techniques are crucial to the monitoring and controlling phase. I would go so far as to say they are the most important factor for control of the project's schedule and budget. To figure out if the project is on schedule, the team would calculate schedule variance (SV = EV - PV) and the results would tell them if they need to speed things up or if they have extra time. To figure out if they need to skimp in certain areas and spend less, or if they can spend extra they would calculate cost variance (CV = EV - AC). This would tell them where they currently stand in regards to the budget. Both the CV and SV should be used as guides to determine where the company stands in regards to the project, and are thus critical to the monitor and control of the project.

I think its important to remember that the monitoring and control phase occurs throughout the entire lifespan of the project and is always a factor in decision making. With that in mind, the various metrics help greatly since they give quantitative and easy to understand values at any stage that the project is on. The process of calculating these values also does not change as the project progresses.

In the control phase any financial values can change based on the project dynamics. Usually the cost can be seen in the phase before the control phase and after where resources are established and assigned to a specific need. However, if in the control phase it is noticed that resources need to be readjusted, the actual cost can change. There are many aspects of the project that can affect the cost variable and with that in mind, projects can be designed with the risk of these dynamics considered.

Planned value and actual cost matter in the monitoring and controlling phase because they can determine future actions that can be taken by the company. If the company is ahead of budget and ahead of time then they may be able to pursue a more advanced product and could spend more time in the design phase. Also, they can now allocate more resources to marketing so that they can branch to other potential buyers and from there gain more potential stakeholder and investors. By looking at where the team is in terms of the project and success rate, they can get a more accurate time table for the rest of the project. If the tea does not monitor it's actual cost then they can fall over budget and be very tight on money or may have to fold the project if the funds run out and the project manager had no idea the funds were running low. By knowing the actual cost, you can develop a control scheme that can help reduce the risk of your project failing.

I think it’s little difficult to add a new statement to this conversation, as everyone here has made very good points, but here is my 2 cents.
The monitoring and controlling phase are seen throughout the project to evaluate risk, and lower cost. We know that the PV and AV along with the EV dictate either a positive or negative SV and CV. I think it is important for the monitoring and controlling phase to look after these numbers to make sure you are staying as positive as you can. Having an idea about where the money is, you can understand what resources you need to use to keep it on schedule. Without their help the budget would be all over the place.

It is the first element of earned value management. Planned Value is the approved value of the work to be completed in a given time. It is the value that should have earned as per the schedule. Planned Value (PV) is the authorized budget assigned to work to be accomplished for an activity or WBS component. This is the second element of earned value management. Actual Cost is the total cost incurred for the actual work completed to date. In other words, it is the amount of money you have spent to date. Actual Cost (AC) is the total cost incurred in accomplishing work performed for an activity or WBS component. Planned value and actual cost is important because it includes the cost elements such as direct costs, direct hours and indirect costs which can be traced from actual invoice. It helps the project to be in control and in budget.

Time is money and in order the project to run, money is involve. Monitoring and controlling phase will take time and there is a planned dates where a predicted value is targeted and reached as plan. After everything is completed there is an actual cost of what the project ends up with. This is the final cost where the cost is gather through the whole time of the project.

The planned value (PV) and the actual cost (AC) can be thought of as one the deciding factors for the success of the project. Since having an actual cost exceeding the planned cost can be a sign of poor budget planning of the project which may be due to a reason that a particular cost was not considered during the planning phase or another reason could be poor performance of the team which led to the increased number of resources and increased number of paid work hours.

The planned value and actual cost serve as points of comparison throughout the project to monitor what the current value of the project is to what the planned value is. And the actual cost helps determine how much it will actually cost and if your budget is realistic. Being able to track this throughout the project is important rather than waiting until you're close to the deadline to check whether you're over budget or behind schedule. Detecting that there is a problem with the budget and scheduling will also cause you to look into what is slowing the project down and fix the problem so as to save time and money.