The tools and techniques recommended for the PMBOK‘s perform quality control include the
cause–and–effect diagram, control charts, flowcharting, histograms, Pareto charts, run charts, scatter
diagrams, statistical sampling, inspection, and defect repair reviews. Cause and effect (fishbone)
diagrams are a diagramming technique used to explore potential and real causes of problems. The
fishbone diagram typically organizes problems into categories relevant to the industry and allows project
team members to work backward from major problems (outputs) to identify potential causes (inputs). As
illustrated in the figure, a delay in a corporate intranet implementation could be traced back to a variety
of potential problem areas, including personnel, materials, methods, and environmental factors. Each of
these main factors could in turn be the result of several different issues. Personnel problems might
include inexperienced programmers, too few people working on the project, or personality conflicts
among those working on the project. Similarly, materials related issues causing project delays might
include delays in hardware shipments, incorrect shipments, or materials damaged in transit.. Fishbone
diagrams are a tool for structuring the project team‘s thinking about potential problem areas and then
uncovering the specific causes of problems in those areas.
Control charts are graphical, time–based charts used to display process results. These charts can be used
to determine whether process deviations are the result of random or systematic causes. Normally
fluctuations around the mean, or target value, on such a chart will be random. Control charts provide a
visual tool for the project team to examine these fluctuations. Sudden systematic results on one side of the
target value might require an investigation by the target team.
A flowchart is a graphical representation of a process. Flowcharting helps to analyze how problems
occur so that approaches can be developed to deal with them. A histogram is a bar chart showing a
distribution of variables, with the height of each column representing the relative frequency of a quality
problem. As an example, a histogram could be used to show categories of objects along with the
frequency of their occurrence. One such application of a histogram is a Pareto diagram, which shows the
various types of problems being encountered in a project, along with each problem’s frequency. Pareto
diagrams were named based on Pareto’s law, or the 80/20 rule, which states that 80 percent of problems
are the result of 20 percent of the causes. By helping identify those problems occurring most frequently,
the Pareto diagram gives to the project team guidance on what problems are most critical to solve.
Run charts show trends in a process over time, variation over time, or declines or improvements in a
process over time. These charts are used for trend analysis. A scatter diagram represents the pattern of
relationship between two variables. The quality team can use this tool to study and identify the possible
relationship between changes observed in the variables. Statistical sampling involves selecting a random
sample from a population in order to infer characteristics about that population. Such sampling might be
integrated into a scatter plot. Inspection consists of measurement and testing procedures to determine
whether results conform to the particular project standards. Inspection should be performed throughout
the project and throughout each of the project phases. Defect repair review is an action taken to ensure
that the project defects are repaired and brought into compliance with standards.