That arises from inaccurate sampling frame, data clarification or verification methods, reporting or coding of data, and/or specifications. It may also arise from poorly designed survey questionnaires, improper sample allocation and selection procedures, and/or errors in estimation methodology.
riff (rÉªf) n. 1. an ostinato melodic phrase accompanying a soloist in jazz or rock music. 2. any variation or improvisation, as on an idea. v.i. 3. to perform a riff. [1930â35; perhaps alter. of refrain 2] riff Past participle: riffed Gerund: riffing
Definition of tread for Students. 1  1 : the action, manner, or sound of stepping or walking. 2  2 : a mark made by a tire rolling over the ground. 3  3 : the part of something (as a shoe or tire) that touches a surface. 4  4 : the part of a step that is stepped on stair treads.