The page will support you in satisfying Writing Learning Objective: 

REASONING - Develop ideas using effective reasoning and productive patterns of organization (claim-evidence-reasoning, cause-effect, compare-contrast, etc.). 

Learning Objectives

You should be able to 

Why Should You Care About Rhetorical Strategies When Writing Engineering Lab Reports?

Typically, the audience aims to learn a student’s thoughts through reading lab data analysis and interpretation results. They want to read your main ideas or how you apply technical meaning to the lab data. Therefore, lab report writers need to make their own points or claims based on the factual lab data as the primary source and supported by, or compared to, secondary sources (outside references).

Opinion versus Claim in Engineering Lab Reports

Out of the Three (Logical, Ethical, and Emotional) Appeals of Argument, Which One do Engineers Mostly Use in Reports?

Use Logical Appeals
Strong arguments have a balance of all three argumentative appeals: logical(logos), ethical(ethos), and emotional(pathos). However, engineers, typically, do not value emotional appeals because lab reports aim to deliver factual, credible, but impersonal technical information to the audience. 

Claim-Evidence-Warrant: Three Parts of a Logical Appeal


An answer (or a finding) to the problem you defined or investigated. Your understanding (or main idea) to present to the audience.

Example: 1045 medium carbon steel is harder than 1008 low carbon steel at the room temperature.

Evidence (Data)

Lab data used to support the claim.

Example: The lab data from Table 1 show the average hardness of 1008 steel coupons is 85 HRB while that of 1045 steel is 99 HRB.

Warrant (REasoning)

Connecting your claim and the evidence logically using engineering principles. Often, secondary sources (other’s data, ideas, and scholarship) can be used for language and further support of the claim.

Example: Addition of carbon as an alloying element in ferrous alloys can create local nonuniformity in the lattice, which makes plastic deformation more difficult by impeding dislocation motion [reference to secondary source].

Common Mistakes