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. 1  1a (1) : the part of a wheel or tire that makes contact with a road or rail (2) : the pattern of ridges or grooves made or cut in the face of a tireb : the part of a shoe or boot sole that touches the ground; also : the pattern on the bottom of a sole. 2  2a : the upper horizontal part of a stepb : the width of such a tread.