The closeness of agreement between individual results obtained in the normal and correct operation of the same method on identical test material, but under different test conditions (such as different operators, different apparatus, different laboratories). (ISO)

The reproducibility of core and log measurements can be checked properly in the laboratory. However, it is difficult to check the reproducibility of downhole log measurements because of the problem of ensuring that the same test material is used, in other words that the same volume of formation is measured each time, or that the formation fluids have not changed.