Before revision: Reasons for the effect Examples NASA quotes the following progress ratios in experience curves from different industries: Cost Estimating Web Site - Learning Curve Calculator Aerospace: 85%DIF < Shipbuilding: 80-85%DIF < Complex machine tools for new models: 75–85%DIF < Repetitive electronics manufacturing: 90–95%DIF < Repetitive machining or punch-press operations: 90–95%DIF < Repetitive electrical operations: 75–85%DIF < Repetitive welding operations: 90%DIF < Raw materials: 93–96%DIF < Purchased parts: 85–88%DIF < The primary reason for why experience and learning curve effects apply is the complex processes of learning involved.
After revision: Reasons for the effect  The primary reason for why experience and learning curve effects apply is the complex processes of learning involved.