1) statistical quality control:

Statistical quality control refers to the use of statistical methods in the monitoring and maintaining of the quality of products and services. One method, referred to as acceptance sampling, can be used when a decision must be made to accept or reject a group of parts or items based on the quality found in a sample. A second method, referred to as statistical process control, uses graphical displays known as control charts to determine whether a process should be continued or should be adjusted to achieve the desired quality.

All the tools of SQC uses different tools to analyze quality problem: 1. Descriptive statistic 2. Statistical process control 3. Acceptance sampling

Statistical process control:

Statistical process control uses sampling and statistical methods to monitor the quality of an ongoing process such as a production operation. A graphical display referred to as a control chart provides a basis for deciding whether the variation in the output of a process is due to common causes (randomly occurring variations) or to out-of-the-ordinary assignable causes. Whenever assignable causes are identified, a decision can be made to adjust the process in order to bring the output back to acceptable quality levels.

Control charts can be classified by the type of data they contain. For instance, an x̄-chart is employed in situations where a sample mean is used to measure the quality of the output. Quantitative data such as length, weight, and temperature can be monitored with an x̄-chart. Process variability can be monitored using a range or R-chart. In cases in which the quality of output is measured in terms of the number of defectives or the proportion of defectives in the sample, an np-chart or a p-chart can be used.

2) Resource leveling:

n project management, resource leveling is defined by A Guide to the Project Management Body of Knowledge (PMBOK Guide) as "A technique in which start and finish dates are adjusted based on resource limitation with the goal of balancing demand for resources with the available supply. Resource leveling problem could be formulated as an optimization problem The problem could be solved by different optimization algorithms such as exact algorithms or meta-heuristic methods.

When performing project planning activities, the manager will attempt to schedule certain tasks simultaneously. When more resources such as machines or people are needed than are available, or perhaps a specific person is needed in both tasks, the tasks will have to be rescheduled concurrently or even sequentially to manage the constraint. Project planning resource leveling is the process of resolving these conflicts. It can also be used to balance the workload of primary resources over the course of the project[s], usually at the expense of one of the traditional triple constraints (time, cost, scope).

When using specially designed project software, leveling typically means resolving conflicts or over allocations in the project plan by allowing the software to calculate delays and update tasks automatically. Project management software leveling requires delaying tasks until resources are available. In more complex environments, resources could be allocated across multiple, concurrent projects thus requiring the process of resource leveling to be performed at company level. In either definition, leveling could result in a later project finish date if the tasks affected are in the critical path.

3) Cost slop:

Mathematically, we can say,

$\text{Cost slope = Crash cost - Normal cost/Normal time - Crash time}$

In simple words, we can say that cost slope of an activity is the increase in cost of an activity by reducing the duration by one unit.

Conducting a crash programme usually result in an increase in cost of those activities that are constructed under the crash programme. In order to keep the total increase in cost to a minimum, it is necessary to crash those activities which permit reduction in construction time at the least total increase in cost. The reduction in time for a project can be achieved by reducing the duration of one or more activities lying on the critical path.