For example, an indirect performance indicator of a reduction in the number of people smoking is per capita tobacco sales. This information is readily available to governments through their tobacco excise and taxation collection systems, whereas direct information on tobacco consumption requires governments to commission regular statistical surveys. The weakness with relying on performance indicators alone is that they do not challenge the underlying causal model. Outcome indicators are especially unreliable measures of program performance where the relationship between outputs and outcomes has not been empirically verified. For this reason, in depth program evaluations complement ongoing performance measurement.
Evaluation affords the opportunity to examine the underlying causal model.
The third foundation of program logic is the normative requirement for congruence between program structures, organisational structures and budget appropriations. Under the program logic approach, government resources and activities are organised into a formal hierarchical framework based on the long-term policy objectives to which they contribute. All of the staff and facilities are consequently focused on working towards achieving desired solutions to specific policy problems. Congruence between the program structure and organisational structure is achieved by aligning the program structure of portfolios, programs and subprograms with the organisational structure of departments, divisions and branches. Program or performance budgeting is the mechanism used to achieve fiscal congruence.