About Product Metrics
Product metrics are measurements of attributes that contribute to quality or user satisfaction. Product metrics tend to measure attributes that increase user satisfaction. Product metrics can be measured and reported as part of documentation quality assurance.
An example of an easily obtained metric is the number of typographical errors in a document. A more difficult metric to obtain, but probably more important, is the number of errors. The difference is significant: the statement “Click Fiinsh” contains a typographical error, but the statement “Click Finish” contains two grammatically correct and correctly spelled words but would be erroneous if another step is required instead.
Product metrics are directly useful, but tend to be obtained after the fact.
General examples include the following (note that some terms require further definition for clarity):
- Clarity: Typos per thousand words (goal: 0). Easily measured using spelling checkers.
- Clarity: Percentage of active voice sentences (goal: 90%). Easily measured using grammar checking software.
- Clarity: Percentage of sentences with logical conditions.
- Clarity: Percentage of task-oriented headings.
- Clarity: Number of jargon words per 100 pages, or number of glossary entries per page (goal: minimize). The more terms needing definition, the less clear the text.
- Clarity: Flesch-Kincaid readability index (goal: Grade 8-12). Measure samples only; do not use as sole metric.
- Clarity: Time to read selected passages (goal: varies).
- Accuracy: Errors per thousand procedural steps (goal: 0). Determined through technical review.
- Accuracy: Errors per hundred declarative sentences (goal: 0). Determined through technical review.
- Accuracy: Review comments per page. Determined through technical review.
- Accuracy: Customer complaints (goal: 0). Depends on active customers.
- Accessibility: Index entries per page (goal: 2-4). Measured by inspecting finished index or counting markers in source.
- Accessibility: TOC entries per page (goal: 1-3). Measured by inspecting TOCs.
- Accessibility: Exhibits per page (goal: 0.5). The more exhibits (illustrations, tables, and examples), the more approachable the document.
- Completeness: Support calls per hundred users on information not documented (goal: 0). Improving documentation quality reduces support calls.
- Satisfaction: Average score on customer-satisfaction survey (goal: maximize). Directly but subjectively measures customer satisfaction; results not applicable generally.
- Ease of use: Average number of steps per procedure (goal: 7). The longer the procedure, the more difficult to complete without user error.
- Ease of use: Time to complete task (goal: varies). Determined through usability testing; results task-specific; use customer feedback to validate standards.
- Ease of use: Percentage of tasks users successfully complete (goal: 90%). Determined through usability testing.