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ANOVA: productivity of three operators

Short answer

One-way ANOVA: all three operator totals equal 52, so SS between = 0 and F = 0. F < critical 4.256; the difference in average productivity due to operators is not significant.

Three trained operators work on production of new product. The productivity of the operators are recorded as below:

Operator 110121416
Operator 212111316
Operator 314151211
Using ANOVA test whether the difference in average productivity due to the difference in operators are significant. Use α = 5%

One-way ANOVA is used because the operators are one factor with three levels.

  1. H0: μ₁ = μ₂ = μ₃ (average productivity of the three operators is the same) H1: at least one operator's mean differs (F-test, right-tailed)
  2. Level of significance: α = 0.05
  3. Computations:
Operator 1   n=4  total=52  mean=13.0000
Operator 2   n=4  total=52  mean=13.0000
Operator 3   n=4  total=52  mean=13.0000

Grand total T = 156,  N = 12
Correction factor CF = T²/N = 156²/12 = 2028.0000
Total SS  = Σx² − CF = 2072.0000 − 2028.0000 = 44.0000
SS between = Σ(Ti²/ni) − CF = 2028.0000 − 2028.0000 = 0.0000
SS within  = Total SS − SS between = 44.0000
  1. ANOVA table:
SourceSSd.f.MSF
Between operators0.000020.00000.000
Within (error)44.000094.8889
Total44.000011
  1. Critical value: F(0.05; 2, 9) = 4.256. Reject H0 if F > 4.256.
  2. Decision: the calculated value falls in the acceptance region (p-value = 1.0000), so fail to reject H0.

Conclusion: the difference in average productivity due to operators is not significant.

✓ Answer checked by Claude Sonnet 5.5

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