1.  The Stainless Steel Law: The better designed the outcome evaluation, the less effective the intervention seems.

2. The Iron Law: The expected value of any impact assessment of any large scale social programme is zero.

3. The Brass Law: The more social programs are designed to change individuals, the more likely the net impact of the program will be zero.

4. The Zinc Law of Evaluation: Only those programs that are likely to fail are evaluated.

Peter Rossi: The iron law of evaluation and other metallic rules. Research in Social Problems and Public Policy. 4:3, 1987.
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