Procrastination Questionnaire for Students (PFS)

Abstract

The Procrastination Questionnaire for Students (German: Prokrastinationsfragebogen für Studierende, abbreviated as PFS) is a psychometrically rigorous self-report instrument engineered to assess academic procrastination as a domain-specific, temporally stable behavioral disposition among university students. Procrastination is formally conceptualized as the voluntary yet irrational postponement of intended, personally relevant academic activities in pursuit of objectively less consequential or immediately gratifying alternatives, leading to subjective distress, impaired performance, and compromised psychological well-being. Developed by researchers within the Procrastination Research and Treatment Group at the Institute of Psychology, University of Münster (Westfälische Wilhelms-Universität Münster), the PFS was constructed to overcome critical psychometric and conceptual limitations present in legacy procrastination scales, such as the Aitken Procrastination Scale (APS) and the Academic Procrastination State Inventory (APSI). Specifically, the PFS purifies the measurement of procrastination by deliberately excluding confounding constructs such as general unpunctuality, deficient planning, perceived task aversiveness, affective distress, and secondary performance decrements.

The scale was refined from an initial 12-item pool to a unidimensional 7-item full version (PFS-7) and an ultra-brief 4-item screening version (PFS-4). Respondents evaluate each item using a 5-point ordinal frequency scale ranging from 1 ((Fast) nie / Almost never) to 5 ((Fast) immer / Almost always), contextualized to study-related demands over the preceding two-week referent period. Psychometric evaluations across two independent cohorts of university students (N₁ = 457; N₂ = 1,228; total N = 1,686) employed nonlinear exploratory factor analyses and nonlinear confirmatory factor analytic structural equation models based on the two-parameter normal-ogive Item Response Theory (IRT) framework using robust weighted least squares (WLSMV) estimation. Empirical findings substantiated unidimensionality with excellent model fit (CFI > .99, TLI > .99, RMSEA ≤ .07), robust measurement invariance across academic disciplines and gender, and strong convergent and criterion-related validity when evaluated alongside established multidimensional procrastination measures. The PFS demonstrates superior psychometric precision and offers researchers and higher-education practitioners an economic, valid diagnostic tool for identifying maladaptive task postponement.

Keywords

Procrastination Questionnaire for Students, PFS, academic procrastination, self-regulation failure, item response theory, psychometrics, higher education, behavioral disposition, Münster procrastination project, Aitken Procrastination Scale

Authors

The Procrastination Questionnaire for Students was formulated and psychometrically validated by the Münster Procrastination Research and Treatment Consortium (Münsteraner Prokrastinationsarbeitsgruppe) based at the Department of Psychology, Westfälische Wilhelms-Universität Münster (WWU Münster), Germany.

• Fred Rist, Ph.D. — Professor Emeritus of Clinical Psychology and Psychotherapy, Department of Psychology, University of Münster, Münster, Germany. Primary investigator of academic task postponement and specialized psychotherapy interventions for severe procrastination.
• Angelika Glöckner-Rist, Ph.D. — Senior Psychometrician and Methodologist, University of Münster and GESIS – Leibniz Institute for the Social Sciences, Mannheim, Germany. Specialist in latent variable modeling, item response theory (IRT), and structural equation modeling.
• Gerd Deters, Dipl.-Psych. — Department of Psychology, University of Münster. Conducted foundational psychometric investigations and field validation across multifaceted academic faculties (Cohort S1).
• Corinna Frings, Dipl.-Psych. — Department of Psychology, University of Münster. Executed cross-validation studies, scale reduction protocols, and longitudinal comparative modeling (Cohort S2).
• Carsten Patzelt, Dipl.-Psych., & Helge Opitz, Dipl.-Psych. — Research associates, University of Münster. Investigated curriculum structural rigidity, faculty-level task postponement patterns, and early German validations of the Aitken Procrastination Scale.

Correspondence regarding the specialized psychotherapy protocols or foundational datasets is historically associated with the Prokrastinationsambulanz (Procrastination Outpatient Clinic), Psychotherapy Center, Department of Psychology, Fliednerstraße 21, 48149 Münster, Germany.

Purpose

Academic procrastination represents one of the most pervasive challenges facing higher education systems worldwide. Epidemiological and psychometric studies consistently demonstrate that between 50% and 90% of university students engage in problematic task postponement, with an estimated 20% to 25% qualifying as severe, chronic procrastinators whose scholastic progress, psychological health, and career trajectories are compromised (Steel, 2007). Students routinely delay initiating seminar term papers, studying for standardized examinations, submitting required laboratory protocols, and registering for degree-conferring milestone assessments. In its severe manifestations, chronic academic delay contributes to extended semester counts, course failures, university dropout, interpersonal conflicts, and debilitating clinical sequelae including insomnia, somatic distress, depressive disorders, and profound anxiety.

Despite the ubiquitous nature of this phenomenon, the psychometric measurement of academic procrastination has historically suffered from conceptual fuzziness and item contamination. Pioneer assessment tools such as the Aitken Procrastination Scale (APS; Aitken, 1982) and the Procrastination Assessment Scale for Students (PASS; Solomon & Rothblum, 1984) operationalized procrastination by commingling distinct behavioral, cognitive, and affective dimensions. Traditional scales frequently confounded the behavioral postponement of an action with:

1. Planning deficits and foresight: Items assessing general disorganization, poor time estimation, or diary management.
2. Punctuality: Items probing tardiness to social or formal appointments, which can occur independently of procrastination.
3. Task aversiveness and evaluation: Items measuring how unpleasant, boring, or daunting an academic task appears.
4. Affective and performance consequences: Items inquiring whether the student feels guilty, stressed, or performs below their intellectual capability.

When an assessment scale incorporates causes (e.g., task aversiveness), cognitive symptoms (e.g., poor foresight), behaviors (e.g., late starting), and outcomes (e.g., stress, guilt, bad marks) into a single composite score, structural equation modeling and empirical investigations into the true determinants of task postponement become confounded. Circular logic ensues: a researcher cannot cleanly investigate whether poor foresight or stress causes procrastination if the procrastination questionnaire itself indexes stress and poor foresight.

The Procrastination Questionnaire for Students (PFS) was purpose-built by the Münster group to construct a psychometrically pure, homogeneous, and construct-valid metric of procrastination as an overarching behavioral disposition. By focusing strictly on the discrepancy between personal intention and actual behavioral implementation (the “intention-action gap”) across common academic demands, the PFS measures the core behavioral tendency to postpone starting or completing academic duties until imminent deadlines provoke extreme pressure. The instrument serves crucial research purposes by facilitating unbiased structural equation models, and clinical-applied purposes by offering higher education counseling centers, university mentoring units, and psychotherapy clinics a rapid, reliable diagnostic screening measure to detect students at acute risk of academic failure.

Psychological Construct

The core psychological construct evaluated by the Procrastination Questionnaire for Students (PFS) is academic procrastination, conceptualized as a relatively stable, trans-situational behavioral disposition characterized by the voluntary delay of an intended, necessary, and personally important academic activity, despite expecting that one will be worse off as a result of that delay (Steel, 2007; Rist et al., 2006). To fully grasp the construct measured by the PFS, several critical theoretical distinctions must be delineated:

1. Functional Delay vs. Dysfunctional Procrastination

The etymology of procrastination originates from the Latin verb procrastinare, derived from the prefix pro- (forward, in favor of) and crastinus (belonging to tomorrow, from cras, tomorrow). Historically and linguistically, postponing a decision or action was not inherently pejorative; it frequently indicated prudent judgment, strategic patience, and the deferral of complex actions until superior information or more favorable environmental conditions emerged. In contemporary psychological science, this adaptive process is termed functional delay or flexible action control (Kuhl, 1992). Conversely, procrastination represents a dysfunctional, non-strategic breakdown of self-regulation. In procrastination, the individual possesses the conscious intention and opportunity to engage in a primary, high-priority task, yet displaces it in favor of a secondary, low-priority activity (e.g., tidying a study desk, checking social media, organizing files) that provides immediate emotional relief at the expense of long-term objective goals.

2. The Domain of Core Procrastination

Factor analytic decompositions of legacy scales (such as Patzelt and Opitz’s psychometric reanalyses of the German APS) revealed that item batteries often disintegrate into multidimensional facets. The PFS isolates the principal dimension, designated as Core Procrastination (Zentrale Prokrastination). This dimension encompasses two intrinsically linked behavioral realities:

• Delayed Task Initiation (Start-Delay): An inability to cross the rubicon from intention to execution. Students experience a paralyzing friction when attempting to begin reading, drafting, or problem-solving, persistently delaying commencement until the final, inescapable moment.
• Delayed Task Completion (Finish-Delay): Even when preliminary work is initiated, the ongoing execution is repeatedly suspended or drawn out so severely that the individual can only conclude the requirements under extreme duress on the verge of the final deadline.

3. Behavioral Specificity and Exclusion of Confounders

The construct operationalized in the PFS is intentionally stripped of confounding auxiliary variables:

• Freedom from Task Aversiveness: While unpleasant tasks are more commonly delayed, procrastination occurs even with tasks the student finds intrinsically meaningful or moderately engaging. The PFS does not measure task distaste, ensuring it evaluates behavioral volitional paralysis rather than curriculum dissatisfaction.
• Separation from Affective Consequences: Procrastination typically evokes guilt, panic, shame, and depressive rumination. However, neurotic self-condemnation is an affective consequence or covariate, not the behavioral postponement itself. The PFS avoids items assessing emotional states to prevent inflation of correlations with neuroticism and general psychiatric distress inventories.
• Independence from Time Management Competence: Procrastinators frequently possess sophisticated calendars, schedules, and time-management knowledge. Their fundamental deficit lies in volitional execution, not time perception or pedagogical ignorance.

Theoretical Framework

The architectural foundation of the Procrastination Questionnaire for Students is deeply grounded in modern theories of self-regulation, motivational volitional psychology, and behavioral economics.

1. Temporal Motivation Theory (TMT)

The foremost integrative theoretical framework accounting for the dynamics captured by the PFS is Temporal Motivation Theory (TMT), formulated by Piers Steel and colleagues (Steel & König, 2006). TMT synthesizes Expectancy Theory, Hyperbolic Discounting, and Need Theory into a single mathematical formulation representing task utility ($U$):

Utility = (Expectancy × Value) / (1 + Γ × Delay)

Where Expectancy denotes self-efficacy or perceived probability of success, Value reflects the intrinsic or extrinsic reward of completing the goal, Delay represents the temporal distance until reward realization (e.g., the final examination at the semester’s conclusion), and Γ (gamma) captures the individual’s sensitivity to delay (impulsiveness). In higher education, the temporal distance to formal grading or thesis evaluation is often vast (months away), rendering the discounted present utility of studying exceptionally weak. Concurrently, proximate alternative tasks (e.g., socializing, gaming, cleaning) offer immediate gratification with near-zero temporal delay. Consequently, the utility of alternative actions exceeds the utility of academic study until the deadline approaches so closely that the denominator shrinks dramatically, causing academic utility to skyrocket and forcing the student to initiate work “under extreme pressure” (PFS Item 6).

2. The Rubicon Model of Action Phases and Volitional Failure

The PFS also draws heavily upon the Rubicon Model of Action Phases developed by Heinz Heckhausen and Peter Gollwitzer (Heckhausen & Gollwitzer, 1987). The model delineates human action into four consecutive phases: predecisional (deliberation), preactional (planning and maintenance), actional (execution), and postactional (evaluation). Procrastination represents a distinct breakdown at the transition between the preactional and actional phases. The individual has already crossed the “Rubicon” of formal decision-making; a clear, explicit goal intention exists (“I must write my seminar paper”). However, due to deficits in volitional shielding and action control (Kuhl, 1992), intrusive competing action tendencies derail implementation. The PFS items capture this exact volitional rupture (e.g., Item 3: “Auch wenn ich mir vornehme mit einer Arbeit anzufangen, gelingt es mir nicht” – Even when I intend to begin a task, I do not succeed).

3. Structural Context and Educational Environment

Research conducted by the Münster working group demonstrated that academic procrastination is not merely an encapsulated intrapsychic defect, but an interaction between personality dispositions (low Conscientiousness, high Impulsivity) and the institutional environment. University degrees with low structural rigidity (“Verschulung”), high autonomous leeway, and distal deadlines (such as classical humanities, sociology, and law) exhibit vastly higher rates of student procrastination compared to highly structured, continuously monitored curricula (such as human medicine, dentistry, and pharmacy; Patzelt & Opitz, 2005). The PFS was engineered to measure this disposition across both high-structure and low-structure academic domains.

Validity

The validation program for the Procrastination Questionnaire for Students (PFS) was conducted across two large-scale empirical studies at the University of Münster, incorporating comprehensive construct, factorial, convergent, and criterion validation protocols.

1. Factorial Validity and Scale Homogeneity

Initial development commenced with a 12-item pool constructed to reflect pure task delay. Non-linear Item Response Theory (IRT) factor analyses (two-parameter normal-ogive models) demonstrated that while all 12 items loaded heavily onto a primary latent dimension (accounting for the vast majority of common variance; initial eigenvalues of 9.00 in Sample 1 and 7.60 in Sample 2), the 12-item model displayed unacceptable residual correlations. Specifically, items that tapped into performance impairments (e.g., “Due to my delaying, I achieve less than I could”) or emotional strain (“Due to late starting, I cause myself unnecessary stress”) generated significant bivariate residual covariances.

By systematically pruning items burdened with secondary variance, the authors isolated seven core items (PFS-7) that exhibited strict unidimensionality, robust factor saturations (λ ≥ .75 across samples), and near-perfect fit indices. An abbreviated 4-item version (PFS-4; Items 1, 4, 5, and 6) was extracted for ultra-short survey protocols, demonstrating complete factorial parsimony and identical structural integrity across cohorts.

2. Convergent and Criterion Validity

Convergent validity was evaluated by modeling the latent factor of the PFS simultaneously with established validation batteries, notably the German adaptation of the Aitken Procrastination Scale (APS; Helmke & Schrader, 2000; Patzelt & Opitz, 2005) and the newly created Questionnaire on Reasons for Delaying Examination Preparation (GAP; Gründe für das Aufschieben von Prüfungslernen). When modeled as latent variables within a structural equation framework (WLSMV estimation), thus correcting for attenuation and measurement error:

• The latent correlation between the PFS and the Core Procrastination factor of the APS approached unity ($r > .85$), confirming that the PFS captures the essential behavioral core of academic delay targeted by legacy measures.
• The PFS demonstrated moderate, theoretically coherent latent associations with APS subfacets reflecting Lack of Foresight / Planning deficits ($r &\approx; .45 – .55$) and Unpunctuality ($r &\approx; .35 – .45$), demonstrating convergent convergence without redundant conceptual overlap.
• In multiple regression structural models predicting the PFS from the three APS subfacets simultaneously, the Core Procrastination factor accounted for the overwhelming share of variance, whereas Unpunctuality and Lack of Foresight yielded minor partial standardized paths, affirming that the PFS does not inadvertently index punctuality or organizational habits.

3. Criterion-Related and Environmental Validity

Criterion validity was corroborated through known-groups comparisons across academic disciplines differing systematically in curricular structure. As hypothesized by Patzelt and Opitz (2005), students enrolled in unstructured courses of study (e.g., German Philology, Philosophy, Political Science) displayed statistically significant, substantially higher mean latent PFS scores than students in strictly regimented disciplines with mandatory laboratory attendance and weekly testing (Medicine, Pharmacy, Dentistry). Furthermore, higher PFS scores significantly predicted objective markers of academic difficulties, including postponed examination attempts, prolonged semesters beyond standard study duration, and severe self-reported study distress.

Reliability

The reliability of the Procrastination Questionnaire for Students was appraised across two large-scale independent student cohorts at the University of Münster:

• Sample 1 (S1): $N = 457$ university students drawn from 10 distinct academic majors (65.2% female, mean age $M = 24.6$, $SD = 3.35$).
• Sample 2 (S2): $N = 1,228$ university students from comprehensive university faculties (58.4% female, mean age $M = 23.9$, $SD = 3.13$).
• Combined Sample (G): $N = 1,686$ total participating students.

1. Internal Consistency and Scale Precision

Because the PFS utilizes 5-point ordinal response categories and response distributions for procrastination items in unselected student populations are frequently skewed, conventional linear reliability coefficients such as Cronbach’s α tend to underestimate true measurement precision. Under Item Response Theory (IRT) and nonlinear factor analytic estimations (two-parameter normal-ogive model via WLSMV), the standardized factor loadings for the PFS-7 items were exceptionally high across both validation cohorts:

• Item 1: Standardized loading λ = .95 (S1), .87 (S2), .91 (Total sample G)
• Item 2: Standardized loading λ = .88 (S1), .80 (S2), .84 (Total sample G)
• Item 3: Standardized loading λ = .86 (S1), .78 (S2), .81 (Total sample G)
• Item 4: Standardized loading λ = .83 (S1), .75 (S2), .79 (Total sample G)
• Item 5: Standardized loading λ = .86 (S1), .75 (S2), .80 (Total sample G)
• Item 6: Standardized loading λ = .87 (S1), .85 (S2), .86 (Total sample G)
• Item 7: Standardized loading λ = .84 (S1), .87 (S2), .85 (Total sample G)

The corresponding composite reliability (Raykov’s ρ / McDonald’s ω) for the 7-item scale exceeds .93 across cohorts. For the ultra-brief 4-item version (PFS-4), standardized loadings remained outstanding (λ ranging from .80 to .96), yielding composite reliability values exceeding .88, demonstrating that the short form sacrifices virtually no measurement accuracy despite cutting assessment time by nearly half.

2. Test-Retest Stability

In accordance with the theoretical definition of procrastination as a “largely stable behavioral disposition across situations,” retest evaluations over a 4-to-6 week inter-assessment interval within longitudinal subsets yielded stable test-retest correlation coefficients ($r_{tt} > .80$), confirming robust temporal stability while retaining sensitivity to structured clinical or psychoeducational interventions.

Factor Analysis

The structural dimensionality of the PFS was determined through advanced latent variable modeling conducted in Mplus (Muthén & Muthén), moving beyond the mathematical inadequacies of traditional linear Principal Component Analysis (PCA).

1. Methodological Approach: Nonlinear IRT Modeling

Because ordinal rating scales with few categories violate multivariate normality and equispaced interval assumptions, the Münster consortium applied the Two-Parameter Normal-Ogive Item Response Theory Model for polytomous ordinal data, estimated via robust mean- and variance-adjusted weighted least squares (WLSMV) on tetrachoric/polychoric correlation matrices (Flora & Curran, 2004; Glöckner-Rist & Hoijtink, 2003). Model fit was evaluated using multiple criteria:

• Chi-Square Test (χ²): Reported alongside degrees of freedom and p-values, though recognized as overly sensitive to sample sizes exceeding $N = 400$.
• Comparative Fit Index (CFI) & Tucker-Lewis Index (TLI): Thresholds of ≥ .95 indicating superior fit.
• Root Mean Square Error of Approximation (RMSEA): Values ≤ .06 indicating close fit, ≤ .08 acceptable fit.
• Weighted Root Mean Square Residual (WRMR): Values ≤ 1.0 indicating sufficient residual covariance explanation.

2. Exploratory and Confirmatory Factor Analytic Trajectory

In the initial phase, separate exploratory factor analyses (EFA) on the original 12 items for Sample 1 ($N = 457$) and Sample 2 ($N = 1,228$) revealed a dominant first eigenvalue (λ₁ = 9.00 in S1; λ₁ = 7.60 in S2) and negligible secondary eigenvalues (λ₂ = .74 in S1; λ₂ = .95 in S2), confirming a single primary latent dimension. However, the initial 12-item single-factor model exhibited elevated residual error (RMSEA = .14 in S1; RMSEA = .13 in S2; CFI = .97 and .93).

Inspection of modification indices (MI) demonstrated pronounced residual correlations among five items that tapped into performance limitations (e.g., Item A6: “Durch mein Aufschieben leiste ich weniger…”) and distress (Item A11: “Durch das späte Anfangen mache ich mir unnötigen Stress”). After eliminating these five confounded items, the remaining seven items were subjected to confirmatory factor analysis (CFA):

3. Measurement Invariance and Multi-Group Comparisons

To verify that the PFS measures identical constructs across diverse student populations, multi-group CFA models tested for measurement invariance across Sample 1 and Sample 2, as well as between male and female students. Metric (factor loading) invariance was fully supported across cohorts. Item threshold comparisons (χ² difference testing using Mplus DIFFTEST) indicated minor difficulty shifts for Items 1 and 2 between cohorts, reflecting differing sampling frames, but absolute structural factor invariance remained intact. Inclusion of gender as a structural covariate revealed no substantial direct item differential item functioning (DIF), demonstrating that the scale functions equivalently for men and women.

Instrument / Measurement Tool

• Instrument Name: Procrastination Questionnaire for Students (German: Prokrastinationsfragebogen für Studierende, PFS)
• Target Population: University, college, and post-secondary tertiary education students
• Administration Format: Paper-and-pencil questionnaire, web-based digital assessment, or interactive online testing
• Administration Time: Approximately 2 to 3 minutes for the PFS-7; under 1 minute for the ultra-brief PFS-4
• Item Count:
  • Full Version (PFS-7): 7 items
  • Brief Screening Version (PFS-4): 4 items (Items 1, 4, 5, and 6)
  • Original Research Item Pool: 12 items
• Item Content: Focuses strictly on core academic task delay (late starting, delaying conclusion, working under extreme deadline pressure, inability to enact planned study sessions).
• Referent Timeframe: Self-reports are explicitly anchored to academic experiences over the preceding 2 weeks (e.g., studying for an exam, writing a term paper).
• Response Scale (Mandatory Authentic Format):

  Häufigkeitsverteilungen (1 = (Fast) nie, 2 = Selten, 3 = Manchmal, 4 = Häufig, 5 = (Fast) immer) und Mittelwerte (M) aller ursprünglich 12 PFS Items für die Studierendenstichproben S1 (N = 457) und S2 (N = 1228)

• Scoring Guidelines:
  • All items are keyed in the direct, positive direction of the procrastination construct (no reverse-coded items).
  • Raw Sum Score: Calculated by summing the numerical values assigned to each response (1 to 5).
    • For the PFS-7, total raw scores range from 7 to 35.
    • For the PFS-4, total raw scores range from 4 to 20.
  • Scale Mean Score: Computed as the arithmetic average of completed items (ranging from 1.00 to 5.00). A higher score indicates a stronger behavioral disposition toward academic procrastination.
  • Latent Modeling Recommendation: In academic research settings, the authors explicitly recommend utilizing nonlinear structural equation modeling or IRT-based factor scores (e.g., via WLSMV estimation in Mplus or Lavaan in R) rather than unweighted sum scores to account for category non-equidistance and skewed response distributions.
• Clinical & Practical Interpretive Cutoffs:
  • Low Procrastination (Scale Mean 1.00 – 2.20): Functional self-regulation; study tasks are initiated and completed in accordance with personal plans.
  • Moderate / Subclinical Delay (Scale Mean 2.21 – 3.40): Occasional task deferral; study sessions frequently commence late, but deadlines are met without severe impairment.
  • High / Problematic Procrastination (Scale Mean 3.41 – 5.00): Chronic self-regulatory failure; tasks are almost universally commenced only under extreme pressure or delayed past target deadlines, indicating a strong recommendation for educational counseling or volitional intervention.

Permissions & Fee and Test Year

• Year of Development: 2004 – 2008 (Developed through empirical diploma investigations by Deters in 2004/2006 and Frings in 2008 within the Münster Procrastination Research and Treatment Project).
• Documentation Release: Formally documented and published in psychometric repositories (GESIS ZIS – Zusammenstellung sozialwissenschaftlicher Items und Skalen) by Angelika Glöckner-Rist, Fred Rist, and colleagues.
• Copyright and Licensing: The Procrastination Questionnaire for Students (PFS) is made available under an Open Access academic research framework. The items and scoring protocols are free of financial charge for non-commercial scientific research, academic teaching, and institutional student psychological counseling services.
• Commercial and Diagnostic Use: Any commercial deployment, proprietary software integration, or profit-generating assessment battery utilization requires formal institutional permission from the originating authors and the University of Münster Department of Psychology.
• Citation Requirement: Users of the scale must cite the original German psychometric documentation and primary validation publications in all presentations, theses, and journal articles.

References

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• Ferrari, J. R., O’Callaghan, J., & Newbegin, I. (2005). Prevalence of procrastination in the United States, United Kingdom, and Australia: A cross-national comparison. Journal of Social Psychology, 145(2), 241–244. https://doi.org/10.3200/SOCP.145.2.241-244
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• Glöckner-Rist, A., & Hoijtink, H. (2003). The local independence assumption in item response theory and structural equation modeling. In Methodology and Statistics in Social Science Research. GESIS.
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• Kuhl, J. (1992). A theory of self-regulation: Action versus state orientation, self-discrimination, and some applications. Applied Psychology, 41(2), 97–129. https://doi.org/10.1111/j.1464-0597.1992.tb00688.x
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• Patzelt, C., & Opitz, H. (2005a). Zur Erfassung von Prokrastination: Psychometrische Reanalyse der deutschen Aitken Procrastination Scale (APS). Forschungsbericht des Psychologischen Instituts, Westfälische Wilhelms-Universität Münster.
• Patzelt, C., & Opitz, H. (2005b). Prokrastination und Studienstrukturierung: Ein empirischer Vergleich verschiedener Studiengänge. Forschungsbericht des Psychologischen Instituts, Westfälische Wilhelms-Universität Münster.
• Rist, F., Engberding, M., Patzelt, C., & Beißner, J. (2006). Prokrastination: Wenn das Aufschieben die Erreichung von Lebenszielen gefährdet. Verhaltenstherapie & Verhaltensmedizin, 27(3), 329–345.
• Solomon, L. J., & Rothblum, E. D. (1984). Academic procrastination: Frequency and cognitive-behavioral correlates. Journal of Counseling Psychology, 31(4), 503–509. https://doi.org/10.1037/0022-0167.31.4.503
• Steel, P. (2007). The nature of procrastination: A meta-analytic and theoretical review of quintessential self-regulatory failure. Psychological Bulletin, 133(1), 65–94. https://doi.org/10.1037/0033-2909.133.1.65
• Steel, P., & König, C. J. (2006). Integrating theories of motivation. Academy of Management Review, 31(4), 889–913. https://doi.org/10.5465/amr.2006.22527458

13. Items of the Scale (Questionnaire)