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Chapter 30: Standard Data. Reusing previously determined times to predict standard times for new operations. E.g., predict cost of automotive repairs Can be specialized for a particular industry, company, or process …. Advantages of Using Standard Data. Cost Time study is expensive.

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chapter 30 standard data
Chapter 30: Standard Data
  • Reusing previously determined times to predict standard times for new operations.
    • E.g., predict cost of automotive repairs
  • Can be specialized for a particular industry, company, or process …
advantages of using standard data
Advantages of Using Standard Data
  • Cost
    • Time study is expensive.
    • Standard data allows you to use a table or an equation.
  • Ahead of Production
    • The operation does not have to be observed.
    • Allows estimates to be made for bids, method decisions, and scheduling.
  • Consistency
    • Values come from a bigger database.
    • Random errors tend to cancel over many studies.
    • Consistency is more important than accuracy.
disadvantages of standard data
Disadvantages of Standard Data
  • Imagining the Task
    • The analyst must be very familiar with the task.
    • Analysts may forget rarely done elements.
  • Database Cost
    • Developing the database costs money.
    • There are training and maintenance costs.
motions vs elements
Motions vs. Elements
  • Decision is about level of detail.
  • MTM times are at motion level.
  • An element system has a collection of individual motions.
  • Elements can come from an analysis, time studies, curve fitting, or a combination.
constant vs variable
Constant vs. Variable
  • Each element can be considered either constant or variable.
  • Constant elements either occur or don’t occur.
  • Constant elements tend to have large random error.
  • Variable elements depend on specifics of the situation.
  • Variable elements have smaller random error.
developing the standard
Developing the Standard
  • Plan the work.
  • Classify the data.
  • Group the elements.
  • Analyze the job.
  • Develop the standard.
curve fitting
Curve Fitting
  • To analyze experimental data:
    • Plot the data.
    • Guess several approximate curve shapes.
    • Use a computer to determine the constants for the shapes.
    • Select which equation you want to use.
statistical concepts
Statistical Concepts
  • Least-squares equation
  • Standard error
  • Coefficient of variation
  • Coefficient of determination
  • Coefficient of correlation
  • Residual
curve shapes
Curve Shapes

Y independent of X

  • Y = A
  • Determine that Y is independent of X by looking at the SE.
y independent of x

10

8

6

4

2

[y]

y=4

0 2 4 6 8 10

[x]

Y Independent of X
  • If Y is not related to X (is independent of X), then Y=A, where A is constant.
curve shapes1
Curve Shapes

Y depends on X, 1 variable

  • Y = A + BX
  • Y = AXB
  • Y = AeBX
  • Y = A + BXn
  • Y = X / (A + BX)
  • Y = A + BX + CX2
curve shapes2
Curve Shapes

Y depends on X, multiple variables

  • Y = A + BX + CZ
  • Results in a family of curves
equations for walking
Equations for Walking
  • NOTE: see attached Excel sheet

intercept = ______ slope = _________

r2 = _______ σ = __________

  • Therefore, Walk time is computed as:

t = __________________

  • So, if a new task is added that requires walking 7.4 m, how long should be allowed in the standard?
equations for walk data set
Equations for Walk Data Set

Walk time h = –.13 + .11 (loge Distance, m)

r2 = .966 σ = .012 h

1/Walk time h = .24 – .96 (1/Distance, m)

r2 = .881 σ = .021 h-1