With the increase in the diversity of dairy products and their specifications, the laboratories of New Zealand dairy companies are accredited as the government’s agent to test their products to establish their quality for export. In order for governmental bodies like the Dairy Division to accredit these factories and to guarantee their results, all laboratories seeking this status are required to participate in the interlaboratory comparison program.

The interlaboratory comparison program sends up to 9 different dairy products a month to over 60 dairy company laboratories in New Zealand for the entire dairy season. The activity is coordinated at the national coordinating laboratory while the agency-certified laboratories are under the direct control of 4 regional reference laboratories, depending on their geographical position.

The agency-certified laboratories analyze the product, the results of which are sent to the coordinating laboratory via the regional reference laboratories. The regional reference laboratories scan for gross errors and scrutinize the agency-certified laboratories results using preliminary means.

The national coordinating laboratory analyzes these results for statistics (bias, variability, and consistency) and returns the results to the agency-certified laboratories and the regional reference laboratories. Control charts of their performance are also distributed to aid the quality control function of the agency-certified laboratories.