A tare weight is a calibrated standard that has known mass and uncertainty values and is usually small relative to the size of the masses being compared.		References in this course: M2L4T2, p. 3/20
Weights are classified based on physical conditions and intended usage.  Every weight in each of the weight classes has an assigned tolerance, that is, the maximum amount by which a mass may deviate from its nominal value.  Tolerances are also called "maxiumum permissible errors." 		References in this course: M2L2T4, p. 3/17; M3L1T2, P. 2/29; M3L5T2, p. 9/24
The evaluation of the calibrated mass value and its associated uncertainty to ensure that all are enclosed within the maximum permissible errors.  A weight is considered to be within tolerance when the absolute value of its error plus its uncertainty does not exceed the applicable tolerance. 		References in this course: M3L1T2, P. 2/29
Traceability is the property of a result of a measurement or the value of a standard whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties.		References in this course: M2L1T1, p. 4/13; M3L1T2, P.3/29
In mass measurement, the term "true mass" is used to mean the mass of an object; the property intrinsic to matter. 		References in this course: M2L1T2, p. 27/32
The t-test is another statistical tool we use to compare two sets of data.  The t-test compares the mean values with respect to the standard deviations of both data sets.  Similar to the F-test, if the calculated t value is less than an acceptable limit, then the data sets are considered to be in agreement. 		References in this course: M1L2T3, p. 11/23






