Final answer:
The opinion-based measures not directly observable are d) Subjective, and this type pertains to qualitative data that is variable and based on personal experiences. Quantitative data is numerical and directly measurable. Researchers examining social interactions, such as symbolic interactionists, may prefer qualitative methods like participant observation.
Step-by-step explanation:
The customer-defined standards that are opinion-based measures and cannot be directly observed are Subjective. These standards, often utilized in qualitative research, rely on personal viewpoints and experiences, making them subjective in nature. Quantitative standards, on the other hand, are numeric and can be observed and measured directly.
In the context of surveys or questionnaires, subjective questions are referred to as open questions that allow for a wide range of responses, capturing qualitative data. They could comprise information that reflects internal thoughts or feelings that are not directly observable and are often gathered through written opinions in a natural setting. This contrasts with quantitative data, which pertains to numerical information that can be quantified and is precise, such as the number of times per week something occurs (quantitative discrete) or the duration of an event (quantitative continuous).
For a symbolic interactionist, a research technique that allows for the observation of social interactions and the interpretation of personal meanings, such as Participant observation, would likely be favored over purely quantitative methods.