Each piece may be individually scored, or the portfolio might be assessed merely for the presence of required pieces, or a holistic scoring process might be used and an evaluation made on the basis of an overall impression of the student's collected work. It is common that assessors work together to establish consensus of standards or to ensure greater reliability in evaluation of student work. Established criteria are often used by reviewers and students involved in the process of evaluating progress and achievement of objectives. A scale based on descriptive words or phrases that indicate performance levels is called a rating scale. The scale may be used with rubrics or descriptions of each level of performance.
Reliability is the measure of consistency for an assessment instrument.
The instrument should yield similar results over time with similar populations in similar circumstances. A rubric is an established set of criteria for scoring or rating students' performance on tests, portfolios, writing samples, or other performance tasks. Scoring criteria may include rating scales, checklists, answer keys, and other scoring tools. A package of guidelines intended for people scoring performance assessments. May include instructions for raters, notes on training rates, rating scales, samples of student work exemplifying various levels of performance.