Limitations of a Portfolio Assessment
Portfolios are one way some teachers measure student performance. Employers can also use portfolios for employee evaluations and sometimes to decide what work to submit to clients or competitions. Portfolios can be creative and help sell a student or employee, but portfolios do have limitations. They should be but one part of a complete evaluation or grading process.
Unreliability
Portfolio assessment is subjective, especially in the absence of some sort of rubric. Just like two people might watch the same movie and come away with radically differing opinions, two people might view the same portfolio and draw different conclusions. If the portfolio is simply serving as a snapshot of student or employee work progress and is graded or evaluated on that basis alone, subjectivity might not be a major issue. However, if teachers or employers base the portfolio grade or evaluation on the so-called quality of work, then subjectivity can become a serious limitation.
Selectivity
One type of portfolio, the product portfolio, shows samples of students' or employees' best work. This selectivity can result in misleading impressions. For example, Joe and Nancy are developing portfolios that showcase their best 10 designs. Suppose Joe has 50 strong samples to choose from, and Nancy has only 15 strong samples to choose from. Based on their portfolios alone, Joe and Nancy appear equally skilled, when in fact, Joe has the better designs in general.
Time
Portfolios require time to plan and develop. Teachers and employers set guidelines for what they want to see and how students or employees should present the portfolio. This preparation can be time-consuming, as can reviewing and grading or evaluating each portfolio. Developing a rubric that is as objective as possible also takes time. Having multiple people view portfolios reduces subjectivity but adds to administrative time.
Comparison
Each portfolio is unique, and that uniqueness is both an advantage and a disadvantage. A portfolio is not a standardized test and should not be treated as such. For example, portfolios cannot answer a question such as: "Do freshmen in high school write better paragraphs than eighth-graders?" No way exists to compare skill and progress across students and schools based on portfolios alone. Standardized tests do that task by having tests with the same questions, taken under the same conditions and evaluated by people who do not know whose work they are looking at.
Unreliability
Portfolio assessment is subjective, especially in the absence of some sort of rubric. Just like two people might watch the same movie and come away with radically differing opinions, two people might view the same portfolio and draw different conclusions. If the portfolio is simply serving as a snapshot of student or employee work progress and is graded or evaluated on that basis alone, subjectivity might not be a major issue. However, if teachers or employers base the portfolio grade or evaluation on the so-called quality of work, then subjectivity can become a serious limitation.
Selectivity
One type of portfolio, the product portfolio, shows samples of students' or employees' best work. This selectivity can result in misleading impressions. For example, Joe and Nancy are developing portfolios that showcase their best 10 designs. Suppose Joe has 50 strong samples to choose from, and Nancy has only 15 strong samples to choose from. Based on their portfolios alone, Joe and Nancy appear equally skilled, when in fact, Joe has the better designs in general.
Time
Portfolios require time to plan and develop. Teachers and employers set guidelines for what they want to see and how students or employees should present the portfolio. This preparation can be time-consuming, as can reviewing and grading or evaluating each portfolio. Developing a rubric that is as objective as possible also takes time. Having multiple people view portfolios reduces subjectivity but adds to administrative time.
Comparison
Each portfolio is unique, and that uniqueness is both an advantage and a disadvantage. A portfolio is not a standardized test and should not be treated as such. For example, portfolios cannot answer a question such as: "Do freshmen in high school write better paragraphs than eighth-graders?" No way exists to compare skill and progress across students and schools based on portfolios alone. Standardized tests do that task by having tests with the same questions, taken under the same conditions and evaluated by people who do not know whose work they are looking at.
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