Ralph Westfall

Interviewers as a Source of Error in Surveys

Harper W. Boyd, Ralph Westfall, Ralph L. Westfall, 1955 .

Marketing Research: Text and Cases

Harper W. Boyd, Ralph Westfall, Stanley F. Stasch, 1977 .

Interviewer Bias Revisited

Harper W. Boyd, Ralph Westfall, Ralph L. Westfall, 1965 .

Psychological Factors in Predicting Product Choice

Ralph Westfall, Ralph L. Westfall, 1962 .

Interviewer Bias Once More Revisited

Harper W. Boyd, Ralph Westfall, Ralph L. Westfall, 1970 .