Friendship Inventory (FI-5)

Introduction

The Friendship Inventory (FI-5) is a brief self-report instrument designed to evaluate the quality, reciprocity, and functional characteristics of friendships across key domains of everyday life. Unlike traditional measures that simply assess the number of friends, the FI-5 focuses on the availability, mutuality, and supportive nature of interpersonal relationships. It is widely used in social psychology, developmental research, community health, and studies of social support to examine how friendship networks contribute to psychological well-being and social functioning.

Description

The FI-5 consists of five domains of daily life, including:

  • Work.
  • Leisure and recreation.
  • Religion or spirituality.
  • Financial matters.
  • Family relationships.

For each domain, participants report:

  • The number of people they consider friends.
  • The number of friends they can rely on when they need help.
  • The number of friends who would seek support from them in return.

Rather than producing a traditional Likert-type score, the inventory evaluates the reciprocity, accessibility, and functionality of friendship networks across different social contexts.

Purpose

The FI-5 is designed to:

  • Assess the quality and reciprocity of friendships.
  • Measure perceived social support.
  • Evaluate functional friendship networks across life domains.
  • Identify strengths and weaknesses in interpersonal relationships.
  • Support research on social integration, loneliness, and psychological well-being.

Administration

The questionnaire is self-administered and generally requires 3–5 minutes to complete. It is suitable for adolescents, adults, and older adults and may be administered in clinical, educational, community, and research settings.

Scoring

The FI-5 does not employ a standardized summed score. Instead, responses are analyzed by examining:

  • The number of reported friendships.
  • The availability of supportive friends.
  • The reciprocity of friendship relationships.
  • Differences across the five life domains.

Higher levels of reciprocity and accessible support indicate stronger and more functional friendship networks, whereas lower reciprocity or limited available support may suggest weaker social integration or reduced interpersonal resources.

Interpretation

The FI-5 provides a multidimensional profile of an individual’s friendship network. Individuals reporting a high degree of reciprocal and supportive friendships generally demonstrate stronger social connectedness, greater resilience, and better psychological well-being. Conversely, discrepancies between perceived friendships and reciprocal support may indicate social isolation, loneliness, or vulnerability during stressful life events.

Statistical Analysis

Psychometric evaluation and analysis of FI-5 data commonly include:

  • Descriptive statistics.
  • Frequency distributions.
  • Cross-tabulation of friendship reciprocity.
  • Correlation analysis.
  • Multiple regression analysis.
  • Network-based descriptive analyses.
  • Group comparisons (t-test, ANOVA, Mann–Whitney U, Kruskal–Wallis).
  • Structural Equation Modeling (SEM) when incorporated into broader psychosocial models.

Because the FI-5 generates count-based and relationship-specific data, both quantitative and qualitative analyses can be performed depending on the study objectives.

Applications

The FI-5 is widely used in:

  • Social psychology.
  • Community psychology.
  • Health psychology.
  • Developmental psychology.
  • Gerontology.
  • Social support research.
  • Loneliness and social isolation studies.
  • Cross-cultural research on interpersonal relationships.

Advantages

  • Brief and easy to administer.
  • Focuses on functional and reciprocal friendships rather than simple network size.
  • Applicable across diverse age groups.
  • Suitable for both quantitative and qualitative analyses.
  • Provides valuable information about social support in multiple life domains.

Limitations

The FI-5 relies on self-reported perceptions of friendship and may be influenced by recall bias, social desirability, and cultural differences in the definition of friendship. Because it does not generate a standardized total score, interpretation depends on the pattern of responses and the research objectives. Results should be considered alongside complementary measures of social support, loneliness, and interpersonal functioning.

References

Malikiosi-Loizos, M., & Anderson, L. R. (1999). Accessible Friendships, Inclusive Friendships, Reciprocated Friendships as Related to Social and Emotional Loneliness in Greece and the USA. European Psychologist, 4(3), 165–178.

Cohen, S., Underwood, L. G., & Gottlieb, B. H. (2000). Social Support Measurement and Intervention: A Guide for Health and Social Scientists.

House, J. S. (1981). Work Stress and Social Support.8.