Experimental methods in chemical engineering: The scientific method versus engineering design methodology

Abstract

Engineering graduate students confuse the scientific method and problem solving when presenting their pre‐doctoral exams and theses: Science discourse adopts question and hypotheses to assert and establish a study's rationale, while it is problem and objectives in engineering design. Here, we contrast the features of the scientific method and engineering design and recommend guidelines for writing hypotheses. For the motivation section of an engineering thesis, we advocate that students include: (i) a problem statement, (ii) knowledge gap (originality, contribution, justification), (iii) objectives, (iv) questions, and (v) hypotheses. When engineers do articulate hypotheses and objectives, they express activities required to complete the research rather than identifying contributions to knowledge related to scientific fundamentals or first principles. We introduce a verb taxonomy for engineering research beginning with the least to the most pertinent: (i) perform—feeble verbs that represent mundane redundant tasks (study, investigate); (ii) describe—passive verbs that chronicle observations; (iii) alter—optimize is the most common verb among this category; (iv) develop—develop and design imply a higher level of originality than alter; and (v) create—these verbs relate directly to fundamentals and core engineering processes like synthesize, functionalize, and polymerize. Hypothesis testing should be the basis of an experimental thesis and must be falsifiable, which requires statistical descriptors—mean and standard deviation, standard error, or confidence interval. We review uncertainty and tests for outliers and blunders, to generate statistical descriptors and contract Chauvenet's criterion, Pierce's criterion, Tukey's interquartile range, and the moving range test.