Value Stream Mapping (VSM) is the Lean tool specifically designed to visualize and analyze the flow of materials and information, making waste like waiting (one of the 8 wastes) explicitly visible. While 5S organizes the workspace, SMED reduces changeover time, and Takt Time sets the production pace, VSM is the primary tool for identifying and planning the removal of non-value-added steps like delays.

For a skewed distribution (non-normal), the mean is heavily influenced by the extreme values in the long tail. The median, which is the middle value when data is ordered, provides a more robust and representative measure of the ‘typical’ or central call duration in this scenario. The mode is the most frequent value, and standard deviation is a measure of spread, not central tendency.

The core principle of the Improve phase is to base decisions on data. While Solution B has experimental data, it may not account for all real-world process variables. A pilot study validates the solution’s effectiveness in the actual operational context, manages risk, and can build stakeholder buy-in. It balances the need for data-driven decisions with practical implementation wisdom.

A run of eight (or more) points on one side of the centerline is one of the standard Western Electric rules for detecting non-random patterns in a control chart. It signals that the process mean has likely shifted, indicating the presence of a special cause of variation that should be investigated, even though no single point has breached the control limits.

Cp (Process Capability Index) measures the potential capability of a process by comparing the process spread (6σ) to the specification width, assuming the process is centered. Cpk (Process Capability Index, adjusted for centering) measures the actual capability by considering both the spread and the centering of the process. Calculating both tells you if the process variation is low enough (Cp) AND if it is correctly centered on the target (Cpk).

Sustaining gains requires active, ongoing systems, not passive communication. A one-time memo provides no mechanism for monitoring, response, or reinforcement. Effective control methods include documented plans (A), training (B), and ongoing monitoring with accountability (D), which embed the new process into the daily work routine.

In hypothesis testing, if the p-value is less than the chosen significance level (alpha), we reject the null hypothesis. A p-value of 0.03 < alpha of 0.05 provides sufficient statistical evidence to conclude that the observed difference in scores is unlikely to be due to random chance alone. It does not 'prove' the alternative (option C), but indicates the data is inconsistent with the assumption of no difference.

A core rule of brainstorming is to defer judgment—no criticism of ideas during the idea generation phase. Critiquing ideas as they are presented (a form of convergent thinking) stifles creativity, discourages participation, and prematurely kills potential ideas before the team can fully explore them. This inhibits the divergent thinking needed to generate a broad set of possible causes.

R-squared (the coefficient of determination) represents the proportion of the variance in the dependent variable (yield) that is predictable from the independent variable (temperature). An R² of 0.89 means 89% of the variability in yield is accounted for by changes in temperature in this linear model. It does not imply causation (A), is not the correlation coefficient r (B is incorrect as r = sqrt(0.89) ≈ 0.94), and is not a probability value (D).

Value Stream Mapping (VSM) is the Lean tool specifically designed to visualize and analyze the flow of materials and information, making waste like waiting (one of the 8 wastes) explicitly visible. While 5S organizes the workspace, SMED reduces changeover time, and Takt Time sets the production pace, VSM is the primary tool for identifying and planning the removal of non-value-added steps like delays.0