Project+ quality and performance charts

Histogram

What it is:

• A bar chart showing the frequency distribution of data.

Use:

• Identify patterns, variations, or trends in data.

• Common in quality control to see how often defects occur.

Pareto Chart

What it is:

• A bar chart showing causes of problems in descending order with a cumulative line.

• Based on the 80/20 rule: ~80% of problems come from ~20% of causes.

Use:

• Identify the most significant issues to prioritize improvement efforts.

Example:

• Bars: Types of errors

• Line: Cumulative percentage of total errors

Run Chart

What it is:

• A line chart showing data points over time to identify trends or patterns.

Use:

• Track performance over time, detect shifts, cycles, or trends.

Example:

• X-axis: Time (days/weeks)

• Y-axis: Number of defects or performance metric

Scatter Diagram

What it is:

• A plot of two variables to identify relationships or correlations.

Use:

• Determine if changes in one variable affect another.

• Helps in root cause analysis and quality improvement.

Example:

• X-axis: Hours of training

• Y-axis: Number of errors

• Pattern shows correlation

Fishbone / Ishikawa Diagram

What it is:

• A cause-and-effect diagram shaped like a fish skeleton.

Use:

• Identify root causes of a problem by categorizing potential causes.

• Categories often include: People, Process, Materials, Machines, Environment, Methods

Example:

• Problem: Software deployment delays

• Causes: Lack of training, poor testing process, insufficient resources

Control Chart

• Is used to monitor process performance over time.

• It typically shows:

  • Upper Control Limit (UCL) → the maximum acceptable value

  • Lower Control Limit (LCL) → the minimum acceptable value

  • Centerline → average or expected value

• If a plot point is above the UCL, it means that the task took longer than expected.

• If a point is below the LCL, it means the task was faster than expected.

• Occasional points above or below the limits don’t necessarily mean the entire process is out of control—they just indicate specific deviations.

Decision Tree

What it is:

• A tree-like diagram used to map decisions and possible outcomes.

Use:

• Evaluate options, risks, and consequences.

• Assign probabilities and expected values to make informed choices.

Example:

• Decision: Build in-house vs. outsource

• Branches: Cost, risk, timeline for each option

Law of diminishing returns chart

• Compare input (cost, effort, resources) against output (benefits, quality improvements)

• Visually show the point where additional investment produces smaller incremental gains

• Help stakeholders make informed decisions about resource allocation