Is Teaching Analogous to a Manufacturing Process?

Evaluating teachers and teaching is challenging. Student ratings of my teaching exhibit large variances, with long tails. If one considers teaching as an I/O process

Inputs ----> Value Addition Processes ----> Outputs

the differences between manufacturing and teaching become visible. Measuring the mean and variance of the outputs, and the deviation from the desired or set tolerances is the starting point for investigation. However the first step in addressing process deficiencies is to ensure that inputs are within tight tolerances. If inputs vary widely, adapting the value addition processes to produce consistent outputs can be very challenging. How does one define "consistent" inputs in education? How can one ensure "consistent" inputs when standards are set at the "local" level?

Formula to Grade Teachers’ Skill Gains Acceptance, and Critics - NYTimes.com: "Use of value-added modeling is exploding nationwide. Hundreds of school systems, including those in Chicago, New York and Washington, are already using it to measure the performance of schools or teachers. Many more are expected to join them, partly because the Obama administration has prodded states and districts to develop more effective teacher-evaluation systems than traditional classroom observation by administrators.

Though the value-added method is often used to help educators improve their classroom teaching, it has also been a factor in deciding who receives bonuses, how much they are and even who gets fired."