# Model Correlation

The Model Correlation utility determines the degree of similarity or correlation between two sets of results.

The Model Correlation utility determines the degree of similarity or correlation between two sets of results.

**Modal Assurance Criterion (MAC)**

Modal Assurance Criterion (MAC) is a measure of the correlation between two vibration shapes.**PreTest**

PreTest allows prediction and optimization of the sensor locations (accelerometers) for measurements and directions along with test excitation point location, a very important step in the experimental modal analysis process directly affecting the accuracy of test results. Driving point residue (DPR) calculation gives information on optimum point for excitation location.**Frequency Response Assurance Criterion (FRAC)**

Frequency Response Assurance Criterion (FRAC) is a measure of the correlation between two frequency response functions (FRFs) representing the same input-output relationship.