Which of the following would be measured subjectively to develop a baseline:

Subjective measurement relies on personal judgment, opinion, or perception rather than on quantifiable, objective facts. "Understandability of training material" is a qualitative attribute. Its measurement is inherently subjective as it depends on an individual's interpretation and comprehension, which is typically captured through surveys, ratings, or user feedback. Establishing a baseline for understandability allows an organization to measure the effectiveness of future improvements to the training material based on user perception. The other options represent objective measures because they are based on direct, verifiable counts or data points that are not subject to personal opinion.

A. Number of people assigned a project: This is an objective and discrete count, not a subjective assessment.

B. Projects completed on schedule: This is an objective measurement based on a factual comparison of planned versus actual completion dates.

D. Lines of code: This is a direct, quantifiable count, making it an objective metric used to measure size.

1. Fenton, N. E., & Bieman, J. (2014). Software Metrics: A Rigorous and Practical Approach, Third Edition. CRC Press. In Chapter 2, "Software Measurement," the authors distinguish between objective measures (e.g., the number of staff on a project) and subjective measures, which involve human estimation or judgment of attributes like "quality" or "complexity." Understandability falls into this subjective category.

2. Pressman, R. S., & Maxim, B. R. (2020). Software Engineering: A Practitioner's Approach (9th ed.). McGraw-Hill Education. Chapter 25, "Software Quality Assurance," discusses the need to measure quality from different viewpoints. Metrics for usability and user satisfaction, which include understandability, are often based on subjective feedback collected via questionnaires and interviews (Section 25.3.2).

3. University of Toronto, Department of Computer Science. (2018). CSC444/2107: Software Engineering - Lecture 5: Quality Assurance. Course materials discuss various quality attributes. Usability attributes, such as how easy a system is to learn or understand, are often assessed through user studies and surveys, which collect subjective data. (Specific reference to lecture slides on Quality Attributes and Metrics).