The Friedman test is a nonparametric analysis of a randomized block experiment. It's parametric counterpart is the Two-Way Analysis of Variance. It requires the data to be balanced (all factor combinations must have the same number of observations) and only one observation per combination.
| Null Hypothesis, H0 | Alternate Hypothesis, H1 |
| All treatment effects = 0 | All treatment effects <> 0 |
At the Excel Menu (For Excel 2007, go to Add-ins first)
Choose ProcessMA > Statistics > Nonparametric > Friedman
In Variable, select the column containing the response data (Numeric, exactly 1 observation per treatment-block combination)
In Treatment, select the column containing treatment levels (>=2 levels)
In Block, select the column containing block levels (>=2 levels)
Click OK
You want to conduct an experiment to assess the strength of concrete with different types of hardener. You prepared 15 blocks of concrete using three types of hardener on five different batches of cement, and tested their strengths.
Open data worksheet by choosing ProcessMA > Tools > Data
In Variable, select BS - Strength
In Treatment, select BT - Hardener
In Block, select BU - Batch
Click OK
For a desired a = 0.05, since p = 0.4493 > a, we fail to reject H0. Therefore, we conclude that there is no significant evidence that the treatment effects are not zero.
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