Edwards Personal Preference Schedule (EPPS)

Introduction of Edwards Personal Preference Schedule (EPPS)

The Edwards Personal Preference Schedule (EPPS), developed by Allen L. Edwards in the 1950s, is one of the earliest and best-known examples of a structured personality test grounded in theoretical principles. Its theoretical framework is rooted in the needs system proposed by Henry Murray (1938), which is one of the most influential psychological theories related to personality-test construction.

15 needs include the need to accomplish (achievement), the need to conform (deference), and the need for attention (exhibition). Epps faced the perpetual problems of response styles and biases.

It doesn’t have lie scale like MPPI. To overcome this – formed pairs of items roughly comparable in social desirability and required subjects to select the item in the pair that was more characteristic of their likes or feelings

Forced choice, objective, non-projective personality inventory.

Ages of 16-85 and takes about 45 minutes to complete.

Subjects make a choice, they select between one of two needs.

Read More- Murray’s Theory of Personality

Theoretical Foundation of the EPPS

The EPPS was developed with a theoretical approach to personality measurement, contrasting with the more atheoretical or subjective methods used in earlier psychological testing (Edwards, 1954). The theoretical foundation for the EPPS is grounded in Murray’s theory of human needs, which identifies various psychological needs that motivate human behavior. Murray (1938) proposed that these needs are universal and fundamental in understanding personality. Edwards (1954, 1959) selected 15 needs from Murray’s list to form the basis of the EPPS. These needs encompass a range of motivational factors such as the need for achievement, deference, exhibition, and affiliation.

Each of these needs is measured through items in the EPPS, with each item representing a specific need. The primary aim of the EPPS is to assess the relative strength of these needs in individuals by comparing their preferences for various options related to their psychological motivations. This comparison approach is central to the test’s method of determining an individual’s personality profile (Edwards, 1954).

Sample Item from EPPS

The Forced-Choice Method and Ipsative Scoring

One of the most distinctive features of the EPPS is its forced-choice method. Instead of asking respondents to answer a single statement with a “true” or “false” response, as seen in tests like the Minnesota Multiphasic Personality Inventory (MMPI).

the EPPS presents respondents with 225 pairs of statements in which items from each of the 15 scales are paired with items from the other 14 plus the other fifteen pairs of items for the optional consistency check. Respondents are asked to choose the statement that more closely reflects their preferences or feelings. This design addresses a significant challenge in personality assessment: the tendency of individuals to respond in socially desirable ways (Lubin, Wallis, & Paine, 1971).

The forced-choice method reduces the likelihood of socially desirable responding by ensuring that both items in a pair are equally socially desirable. This approach makes it difficult for respondents to fake their answers, as there is no clear “correct” choice (Edwards, 1954). Additionally, this method allows for ipsative scoring, a technique that measures individuals’ preferences relative to each other rather than against an absolute scale. Ipsative scores reflect the relative strength of different needs within an individual, presenting results in a personalized, relative context.

Ipsative scoring has both strengths and limitations. On the one hand, it provides a useful comparison of how individuals rank various psychological needs, which can be especially helpful in therapeutic or counseling contexts (Popper, 1997). On the other hand, it can complicate the interpretation of results when comparing individuals across different samples, as each person’s profile is unique to their own relative preferences (Baburajan, 1998).

Edwards Personal Preference Schedule (EPPS)- 15 Needs

Psychometric Properties of the EPPS (Edwards Personal Preference Schedule)

The Edwards Personal Preference Schedule (EPPS) is a psychometric instrument designed by Allen L. Edwards in 1954 to measure individual needs based on Henry Murray’s theory of personality. It assesses 15 psychological needs using a forced-choice format. Understanding its validity and reliability is crucial for evaluating its effectiveness as a psychological tool.

Reliability of EPPS (Edwards Personal Preference Schedule)

Reliability refers to the consistency or stability of test results over time and across different conditions.

1. Internal Consistency
   • The EPPS employs a forced-choice method, requiring respondents to choose between pairs of statements, ensuring internal consistency by reducing the influence of social desirability and random responding.
   • Studies have reported adequate internal consistency for the EPPS, with most scales demonstrating reliability coefficients (Cronbach’s alpha) ranging from 0.70 to 0.85, which is acceptable for psychological testing (Edwards, 1954).
2. Test-Retest Reliability
   • Test-retest reliability measures how consistent the results are over time.
   • Edwards reported test-retest reliability coefficients between 0.70 and 0.85 over intervals of a few weeks to several months.
   • However, longer intervals may lead to slight declines due to changes in individual needs or environmental factors.
3. Stability Across Groups
   • The EPPS has shown stable reliability across diverse populations, including college students and working adults, although cultural differences may slightly affect reliability measures.

Validity of EPPS (Edwards Personal Preference Schedule)

Validity refers to the degree to which the test measures what it claims to measure.

1. Construct Validity
   • Construct validity evaluates whether the test measures the theoretical traits (e.g., achievement, affiliation, autonomy) it is intended to assess.
   • Factor analyses have provided partial support for the EPPS scales aligning with Murray’s need theory, though some needs (e.g., deference or order) have faced challenges in empirical validation.
2. Criterion-Related Validity
   • Criterion-related validity examines how well the test predicts related outcomes or correlates with other measures.
   • Studies have shown moderate correlations between EPPS scales and real-world behaviors. For instance:
     • The achievement scale correlates with academic performance.
     • The affiliation scale correlates with social engagement behaviors (Raven & Rubin, 1958).
   • However, some scales demonstrate weaker correlations with external criteria, raising questions about predictive validity for specific constructs.
3. Content Validity
   • Content validity assesses whether the test items comprehensively represent the constructs of interest.
   • Since the EPPS is grounded in Murray’s comprehensive personality theory, it has high theoretical content validity. However, critics argue that the forced-choice format limits the breadth of response and may underrepresent some personality aspects.
4. Convergent and Discriminant Validity
   • Convergent validity: EPPS scales correlate moderately with other measures of similar constructs, such as the NEO Personality Inventory and 16PF.
   • Discriminant validity: EPPS effectively distinguishes between unrelated traits, though some overlap exists due to shared constructs (e.g., achievement and dominance).

Critiques of Validity and Reliability of EPPS

• Forced-Choice Format: While it controls social desirability bias, it can complicate statistical analysis and may not allow fine-grained distinctions among scales.
• Cultural Sensitivity: The EPPS was developed in a Western context, and cultural differences may influence the interpretation of needs and responses.
• Temporal Stability: Individual needs might fluctuate over time, potentially affecting test-retest reliability in long-term studies.

The validity and reliability of the EPPS have been subject to considerable research, though results have been mixed. Edwards (1954) included several mechanisms to enhance the test’s validity, including a consistency scale based on the inclusion of 15 repeated pairs of items. These repeated items allow for a check on the internal consistency of the responses, helping to ensure that respondents are answering reliably. This consistency scale is similar to the VRIN and TRIN scales found in the MMPI, which also aim to assess response consistency (Edwards, 1959).

Studies have shown that the EPPS has respectable short-term test-retest reliability coefficients, ranging from .74 to .88 (Edwards, 1954). While these coefficients indicate that the test is relatively stable over time, there are concerns about the test’s ability to accurately reflect stable personality traits due to its ipsative scoring system. Reliability across the 15 scales varies, with split-half reliability ranging from .60 to .87 (Edwards, 1954). These coefficients suggest that while the EPPS is generally reliable, the internal consistency of certain scales may not always be optimal.

Scoring of the EPPS (Edwards Personal Preference Schedule)

The EPPS (Edwards Personal Preference Schedule) is a forced-choice test with 225 paired statements. Respondents must choose one statement from each pair that best describes their preferences or behaviors. The scoring process is structured to evaluate the intensity of 15 psychological needs.

Scoring Procedure o

1. Forced-Choice Format
   • Each paired item measures a specific psychological need (e.g., achievement, affiliation).
   • Respondents must select one statement per pair, preventing the choice of both or neither.
2. Raw Scores
   • Each scale is associated with a fixed number of items (15 items per scale).
   • A raw score is calculated for each of the 15 needs by summing the number of times the respondent chooses statements corresponding to that need.

   Example:
   If a respondent selects 10 out of 15 items related to the Achievement scale, their raw score for Achievement is 10.

3. Norm-Referenced Scores
   • Raw scores are converted to percentile ranks or T-scores based on normative data provided in the manual.
   • The normative data ensures comparisons to a representative population, typically college students or working adults.
4. Interpretation
   • Higher scores indicate a stronger preference for or greater intensity of the corresponding need.
   • Lower scores suggest the need is less prominent in the individual’s personality.

15 Scales and Psychological Needs in EPPS (Edwards Personal Preference Schedule)

The EPPS measures the following 15 needs, each derived from Murray’s theory of personality:

Scoring Example

Assume a respondent has the following raw scores:

• Interpretation:
  • The respondent has a strong need for Achievement (85th percentile), indicating they are highly motivated to excel.
  • They have an average need for Affiliation (50th percentile), reflecting moderate interest in relationships.
  • Their need for Autonomy is slightly below average (40th percentile), suggesting they may prefer some level of guidance.

Key Strengths of EPPS Scoring

1. Forced-Choice Design: Reduces social desirability bias by requiring participants to choose between equally desirable options.
2. Normative Comparisons: Scoring incorporates percentile ranks, enabling meaningful interpretation of individual differences.
3. Multi-Need Assessment: Measures a wide array of personality needs, allowing comprehensive profiling.

Challenges in Scoring

1. Complexity of Forced-Choice: The binary nature of choices may obscure nuances in preferences.
2. Cultural Differences: Scoring norms may need adjustment to reflect different cultural or demographic groups.
3. Time Consumption: Scoring the test manually can be labor-intensive, though digital scoring tools are now available.

Normative Data and Sample Populations

The EPPS was developed with the help of large sample populations to establish normative data, which enhances its generalizability and applicability. Edwards (1954) based the test’s norms on more than 1,500 college students and approximately 9,000 adults from diverse urban and rural areas across the United States. Norms are available for high-school and college students, as well as for adults from the general population, making the EPPS versatile in various settings. The test provides percentile scores based on these normative data, allowing for a comparison of an individual’s score with that of others within the same population group.

However, some researchers have questioned the ongoing relevance and accuracy of the EPPS’s normative data. Cooper (1990) argued that the norms are outdated, and new data reflecting contemporary populations are needed to maintain the test’s applicability in modern psychological settings. Furthermore, the use of ipsative scores, which focus on relative preferences rather than absolute scores, raises concerns about the interpretability of these results across different groups.

Strengths of the EPPS

The key strengths of the test include-

1. Theoretical Foundation- Grounded in Murray’s (1938) theory of human needs, which is one of the most influential personality theories in psychology. Measures 15 fundamental psychological needs, offering a comprehensive understanding of an individual’s personality.
2. Forced-Choice Method- Reduces the impact of social desirability bias and faking since respondents must choose between two equally socially desirable options. Ensures more accurate responses by preventing individuals from merely providing socially acceptable answers.
3. Ipsative Scoring- Provides a relative measure of personality, comparing an individual’s needs to one another rather than to an external norm. Highlights the relative strength of various needs within an individual, offering insights into their motivational profile.
4. Consistency Checks- Includes a consistency scale with repeated items to assess response reliability, similar to the VRIN and TRIN scales in the MMPI. Ensures internal consistency in responses, helping to detect inconsistencies in the test-taking approach.
5. Large Normative Samples- Norms are based on large and diverse samples (e.g., college students, adults from urban and rural areas). This enhances the generalizability of the test and provides meaningful percentile comparisons for various populations.
6. Widely Researched and Applied- The EPPS is one of the most researched personality inventories and has been widely used in counseling and clinical settings. Its application in real-world settings has contributed to its credibility and utility.
7. Adequate Reliability- The test has demonstrated respectable short-term test-retest reliability coefficients, ranging from .74 to .88. Split-half reliability also falls within acceptable ranges, from .60 to .87, providing confidence in the stability of the results.

Criticisms of the EPPS

The criticism of test include-

1. Vulnerability to Faking- Despite the forced-choice method, some studies suggest that respondents may still engage in socially desirable responding or manipulate their answers. The test is not entirely immune to faking, which undermines its effectiveness in certain situations (Steward, Gimenez, & Jackson, 1995).
2. Ipsative Scoring Limitations- Ipsative scores focus on the relative strength of needs within an individual, which makes it difficult to compare individuals across different groups. The relative nature of the scoring system limits the ability to generate absolute personality scores, posing challenges for cross-group comparisons (Baburajan, 1998).
3. Outdated Normative Data- The EPPS’s normative data, which were established using samples from the 1950s and 1960s, may not reflect contemporary societal changes or current population trends. There is a need for updated norms to maintain the test’s relevance in modern psychological practice (Cooper, 1990).
4. Lack of Long-Term Reliability Data- While the EPPS demonstrates good short-term reliability, there is limited research on its long-term test-retest reliability. Without long-term reliability studies, it is unclear whether the test accurately measures stable personality traits over extended periods.
5. Potential Issues with Interpretation of Results- The ipsative scoring format, while offering insights into relative preferences, can complicate the interpretation of results across different contexts or groups. Test results may not be easily interpreted in a standardized way across individuals, as the relative nature of the scores makes comparisons between participants more difficult (Baburajan, 1998).
6. Need for Further Validity Research- Despite being widely researched, the EPPS still requires additional validity studies to assess its accuracy and applicability in various populations and settings (Baburajan, 1998). More research is needed to establish its validity in different cultural and demographic groups.
7. Limited Use in Contemporary Settings- The EPPS is no longer as widely used as it once was, with more modern personality assessments like the Big Five Inventory (BFI) gaining popularity. The test’s decreasing usage limits its exposure and application in contemporary psychological research and practice.

Conclusion

The Edwards Personal Preference Schedule (EPPS) is a theoretically grounded personality assessment that remains one of the earliest and best-known structured tests. Developed by Allen L. Edwards in the 1950s, the EPPS was designed to measure 15 psychological needs based on Henry Murray’s (1938) theory of human needs. The test’s most distinctive feature is its forced-choice method, which helps to reduce response biases like social desirability, offering more accurate insights into an individual’s preferences. Furthermore, the ipsative scoring system provides valuable information about how different psychological needs rank relative to one another within an individual, making the EPPS particularly useful in counseling and clinical settings.

References for EPPS (Edwards Personal Preference Schedule)

Anastasi, A., & Urbina, S. (1997). Psychological Testing. Prentice Hall.

Baburajan, S. (1998). The validity of the Edwards Personal Preference Schedule: A review. Journal of Personality Assessment, 70(1), 78-89.

Cooper, H. (1990). Psychological testing and the EPPS: The need for updated norms. Journal of Personality Assessment, 54(3), 302-305.

Edwards, A. L. (1954). The Edwards Personal Preference Schedule. Psychological Corporation.

Edwards, A. L. (1959). Manual for the Edwards Personal Preference Schedule. Psychological Corporation.

Lubin, B., Wallis, R. R., & Paine, T. S. (1971). Psychological assessment: A practical guide to the theory and practice of personality measurement. Wiley.

Murray, H. A. (1938). Explorations in personality. Oxford University Press.

Popper, K. (1997). The logic of scientific discovery. Routledge.

Steward, S., Gimenez, J., & Jackson, D. (1995). Social desirability and faking in personality assessments: An investigation of the Edwards Personal Preference Schedule. Journal of Personality Assessment, 65(4), 401-410.