System and method for producing statistically valid assay means and ranges for quality control materials

A method of establishing a sampling plan for assigning an assay mean and range to a particular lot of a quality control material, the method comprising:

• setting an upper limit for the percentage of the assay range that is due to uncertainty in estimating the mean;
• accessing a database of historical test results obtained from tests performed on prior lots of the quality control material;
• computing at least in part from the historical test results a within-instrument variability estimate that is an estimate of the variability of test results obtained using a single testing instrument on at least one prior lot of the quality control material;
• and
• computing at least in part from the historical test results a between-instrument variability estimate that is an estimate of the variability of test results obtained using different testing instruments on at least one prior lot of the quality control material;
• and
• establishing a sampling plan, based at least in part on the within- and between-instrument variability estimates, to achieve an assay range having a percentage of its width due to uncertainty in estimating the mean, the percentage being at or below the upper limit.

A system for establishing a statistically valid assay mean and assay range for a particular lot of a quality control material, the system comprising:

• a processor;
• a database holding historical test results obtained from tests performed on prior lots of the quality control material;
• and
• a memory readable by the processor, the memory holding processor instructions that when executed by the processor cause the system to
• obtain a number of test results obtained from tests on a number of samples from the particular lot of the quality control material;
• compute a mean of the test results;
• access the database of historical test results obtained from tests performed on prior lots of the quality control material;
• compute at least in part from the historical test results a variability estimate that is an estimate of the variability of test results obtained from tests performed on at least one prior lot of the quality control material;
• receive a specification of a target probability with which a new qualification test result performed on a sample of the new lot of quality control material will fall within the assay range;
• and
• compute, based at least in part on the mean and the variability estimate, a range of test result values within which a result from a qualification test of a sample from the particular lot of the quality control material is expected to fall, with the target probability.

An assay mean and range assignment system for establishing a statistically valid assay mean and assay range for a particular lot of a quality control material, the system comprising:

• a database holding historical test results obtained from tests performed on prior lots of a quality control material;
• a mean determination module that receives a number of test results obtained from tests on a number of samples from a new lot of the quality control material and computes a mean of the test results;
• a variability estimation module that computes at least in part from the historical test results a variability estimate that is an estimate of the variability of test results obtained from tests performed on at least one prior lot of the quality control material;
• and
• a range establishment module that establishes, based at least in part on the mean and the variability estimate, a range of test result values within which a result from a qualification test of a sample from the new lot of the quality control material is expected to fall, with a target probability.