Torbjørn Skardhamar

• Allvin, Annica & Skardhamar, Torbjørn (2026). Stably Unstable? – Testing the Temporal Stability of Spatial Crime Patterns | Journal of Quantitative Criminology | Springer Nature Link. Journal of quantitative criminology. ISSN 0748-4518. doi: 10.1007/s10940-026-09691-5. Fulltekst i vitenarkiv Vis sammendrag

  Criminological research has long suggested that microgeographical crime patterns are remarkably stable over time; however, there is little consensus on how stability should be defined or measured. This study investigates the stability of spatial crime patterns in Oslo, Norway, over two decades. We review definitions and operationalizations of spatial stability and test three central hypotheses. Using 20 years of police-registered crime data, we apply K-means longitudinal clustering to examine crime trends at a 100 × 100 m grid-cell level. We expand upon prior research by explicitly analysing within-cluster variation, conducting separate analyses by crime type, and testing robustness to changes in temporal resolution. We also demonstrate an alternative method using predefined criteria and compare the results. Although cluster-averages or -medians suggest spatial stability, we observe substantial variation within all clusters, suggesting places are easily interpreted to be more stable than they are. Whether most places exhibit low and stable crime trends, or whether chronic hot spots exist in Oslo, depends on the operationalization of stability. The degree of within-cluster variation casts doubts on whether conventional clustering approaches alone provide convincing evidence of persistent patterns, without closer scrutiny. Spatial stability may be overstated when inferred from cluster models relying on annual data. These crime patterns in Oslo are better understood as stably unstable, reflecting patterned variability rather than fixed persistence. Substantial local variation complicates interpretations of long-term stability. We argue for more careful operationalizations of spatial stability, closer attention to within-cluster variation, and greater consideration of temporary hot spots.

• Skardhamar, Torbjørn (2026). Black Ships: What Kind of Martial Art Is Sociology? Theory and society. ISSN 0304-2421. 55. doi: 10.1007/s11186-026-09744-5. Fulltekst i vitenarkiv Vis sammendrag

  Pierre Bourdieu described sociology as a martial art but never specified what kind. The kind matters. The Japanese martial tradition offers a typology he did not draw: -jutsu, oriented toward defeating a real opponent; -do as competition, oriented toward internal scoring within a closed tournament; and -do as formation, oriented toward cultivating the practitioner rather than testing any claim against reality. I use this typology as a diagnostic framework. Sociology is predominantly -do. The costs are visible and cumulative, and they follow a pattern of slow response to external challenges: the credibility revolution, open science, and now AI. Open science and AI reshape what counts as rigorous work across methods, quantitative and qualitative alike. In 1853, Commodore Perry’s Black Ships arrived at Edo Bay, and the Shogunate discovered that two centuries of internal competition had not prepared it for an external force indifferent to its rules. The political order it had sustained did not survive the encounter. Sociology faces a comparable moment. I argue for a -jutsu imperative: not for any particular method, but for pressure-testing by standards the discipline does not control — a standard sociology has already committed to by claiming to produce knowledge about the social world, whether it acknowledges this or not.

• Jukka, Savolainen, & Skardhamar, Torbjørn (2026). The growth of knowledge in criminology: toward a more optimistic appraisal of theoretical progress. Theory and society. ISSN 0304-2421. 55. doi: 10.1007/s11186-026-09740-9. Fulltekst i vitenarkiv Vis sammendrag

  Criminology is often portrayed as theoretically stagnant – a view reinforced by an influential review that interpreted the modest explanatory power of published research as evidence that criminological theory had failed to advance. We argue that this diagnosis rests on the wrong yardstick. Explained variance is neither a necessary nor a sufficient indicator of theoretical progress. Drawing on a post-Popperian conception of scientific growth emphasizing the problem-solving capacity of competing research traditions, we propose evaluating criminological theory according to its ability to resolve empirical puzzles and reduce crime-related harm. We illustrate this approach with two examples. First, evidence from competing theories of desistance has increasingly converged on the view that structural turning points are better understood as facilitators and consequences of change than as exogenous catalysts, shifting attention toward agency, cognitive transformation, and reciprocal processes. Second, routine activities theory emerged in response to the puzzle of rising crime amid postwar prosperity and generated a highly productive research tradition encompassing environmental criminology, hot-spots research, and situational crime prevention. In turn, situational crime prevention translated these theoretical insights into a cumulative body of evidence demonstrating the effectiveness of opportunity-reducing interventions. These episodes suggest that theoretical progress in criminology is best understood in terms of the capacity of competing research traditions to resolve anomalies, generate fruitful lines of inquiry, and produce practical solutions. More broadly, they demonstrate that theoretically pluralistic social sciences are capable of cumulative progress even in the absence of a dominant paradigm.

• Skardhamar, Torbjørn (2026). Query Authorship: A Framework for Systematic AIUse in Social Science. SocArXiv. Fulltekst i vitenarkiv
• Andresen, Anette Marie & Skardhamar, Torbjørn (2026). Rethinking Criminal Onset: Age at First Offence, Persistence, and Sex Differences. Journal of Developmental and Life-Course Criminology. ISSN 2199-4641. 12(1). doi: 10.1007/s40865-026-00315-x. Fulltekst i vitenarkiv Vis sammendrag

  How frequent is criminal onset at each age, and to what extent does onset age predict continued offending across the life course for men and women? Criminological theory and empirical research put emphasis on young offenders, as early onset is a clear risk-factor for persistence, and often assume later onset implies lower risk of continued offending, yet the prevalence and persistence of adult onset remain disputed. It is also contentious whether there is any meaningful onset after reaching adulthood. While it is clear that the risk of onset declines with age, the dominant empirical approach in the literature is to identify the most common trajectory groups, using methods that are less likely to identify segments of unusual offending patterns, such as onset after normative ages. Using nationwide administrative records of solved offences for the resident population of Norway, we provide descriptive accounts of first registered offences in 2010 and subsequent continuation across all ages (N = 22 610; observation window 1982–2020). We find registered onset across all ages for both men and women, and while the risk of continuation declines with age, a non-ignorable number of offenders continue after onset even in older ages among both sexes (21% among men and 23% among women with onset at age 40 or older).

• Skardhamar, Torbjørn (2026). Standards in sociology: Agreeing on principles, disagreeing on ambition. Rationality and Society. ISSN 1043-4631. 38(3), s. 442–445. doi: 10.1177/10434631261464480. Fulltekst i vitenarkiv Vis sammendrag

  Aksoy, Manzo, Birkelund, and Raub have written a thoughtful and well-argued position statement. I agree with most of what they say. My comment is not, therefore, primarily a disagreement but a question about actionable consequences. The three principles they advance — integration of theory and empirics, open science, and engagement with societal debates — are defensible. The problem is what the statement does with them. At each point where the argument reaches an operational conclusion, the language is strong — institutions “must establish” the conditions necessary to sustain open science, the community “should demand” sociology to be open — but the content of the demand is left unspecified. This is a statement that agrees with its own principles but declines to press them.

• Friestad, Christine & Skardhamar, Torbjørn (2025). Criminal Careers in the Making? Characteristics and Trajectories of Juveniles Charged With a Sexual Offense. Sexual Abuse. ISSN 1079-0632. doi: 10.1177/10790632251393988. Fulltekst i vitenarkiv Vis sammendrag

  The present study investigates the onset, persistence and diversity in sexual offending by exploring Norwegian registry data on the social and criminal trajectories of juveniles charged with a sexual crime before the age of criminal responsibility, compared to juveniles charged with other types of offenses. The sample consisted of all persons aged 15 during the period 1997–2005 (N = 388,814). Of those, 19,559 juveniles (5%) were charged with a crime, mostly (83%) of a non-violent nature. For the remaining 16.9% (n = 3,309), the charge involved violence, either non-sexual (n = 2,991, 15.3% of those charged) or sexual (n = 318, 1.6% of those charged). Proportional hazard models were used to investigate background characteristics and risk of recidivism. Early onset of offending was related to a more disadvantaged background. Juveniles charged with violent and sexual offenses were generally younger and had more charges against them than juveniles charged with any other crimes. Early sexual crime carried higher hazard rate (HR) of future sexual crime (HR = 3.6) than early violent (HR = 1.9) and other crimes (HR = 1.4). The risk of later violent crime was similar among those with early onset violent (HR = 2.8) and sexual (HR = 2.5) crime, and higher than for early onset general crime (HR = 1.7). Since violent crime has a higher base rate than sexual crime, violence is more dominant in the criminal careers of people with early onset sexual offending. However, the majority of adult sexual criminal charges are raised against persons without a juvenile criminal record.

• Svendsen, Vegard Testad; Stavseth, Marianne Riksheim; Skardhamar, Torbjørn; Havnes, Ingrid Amalia & Bukten, Anne (2025). Substance use disorders, severe mental illness and risk of reoffending among women released from prison: a national cohort study. Scientific Reports. 15(1). doi: 10.1038/s41598-025-00215-y. Fulltekst i vitenarkiv Vis sammendrag

  Women with a clinical history of a severe mental illness (SMI) or multiple mental disorders involving substance use disorder (SUD) might be at increased risk of re-offending after release from prison. This retrospective cohort study merged data from the Norwegian prison release study (nPRIS) with other registry sources. All women released from a Norwegian prison between 2011–2019 were followed for two years after date of release. Adjusting for several known risk factors, we used logistic regression to estimate risk of violent (VR), drug-related (DR) or other reoffending (ORE) after release among women with a history of SUD and severe mental illness (SUD-SMI), SMI, SUD and other mental illness (SUD-OMI) or a history of multiple SUDs (POLY-SUD) in comparison to a reference population with no history of such disorders or combination of disorders. Relative to the reference population, after adjusting for other relevant risk factors, women with a history of SUD-SMI (OR VR 2.27, 95% CI 1.37–3.76; OR DR 2.10, 95% CI 1.49–2.95), SUD-OMI (OR VR 1.81, 95% CI 1.11–2.47; OR DR 1.53, 95% CI 1.11–2.10) or POLY-SUD (OR VR 1.87, 95% CI 1.04–3.31; OR DR 2.51, 95% CI 1.80–3.49) were at significantly greater risk of violent and drug-related reoffending. Women with a history of SMI were at significantly greater risk of other reoffending (OR ORE 2.64, 95% CI 1.21–5.30). Women with a clinical history of a severe mental illness (SMI) or multiple mental disorders involving substance use disorder (SUD) have an elevated risk reoffending.

• Svendsen, Vegard Gjerden; Bukten, Anne; Skardhamar, Torbjørn & Stavseth, Marianne Riksheim (2024). Mortality in women with a history of incarceration in Norway: a 20-year national cohort study. International Journal of Epidemiology. ISSN 0300-5771. 53(2). doi: 10.1093/ije/dyae032. Fulltekst i vitenarkiv Vis sammendrag

  Background Women carry a substantial burden of psychiatric, somatic and lifestyle-related morbidity in the prison context. By describing causes of death and estimating the risk and burden of mortality compared with the general population, this study investigates how mortality operates in this highly marginalized and under-researched population. Methods In this registry-based study of all women incarcerated in Norwegian prisons from 2000 to 2019 (N = 11 313), we calculated crude mortality rates, years of lost life and, by using mortality in age-matched women from the general population as a reference, age-standardized mortality ratios and years of lost life rates. Results Over a mean follow-up time of 10.7 years, at a median age of 50 years, 9% of the population had died (n = 1005). Most deaths (80%) were premature deaths from an avoidable cause. Drug-induced causes and deaths from major non-communicable diseases (NCDs) were most frequent (both 32%). Compared with women in the general population, women with a history of incarceration were more likely to die from any cause. Trends in annual age-standardized years of lost life rates suggest that the mortality burden associated with major NCDs has gradually replaced drug-induced causes. Conclusions Women with a history of incarceration die at a greater rate than their peers and largely from avoidable causes. The profile of causes contributing to the substantial burden of mortality placed on this population has changed over time and has important implications for future efforts to reduce morbidity and the risk of premature death following release from prison.

Se alle arbeider i NVA

• Skardhamar, Torbjørn (2026). Systematisk KI-bruk løser problemet med KI på eksamen. Fulltekst i vitenarkiv Vis sammendrag

  Å formulere presise instruksjoner til KI, vurdere output kritisk og begrunne valgene man tar, er kognitivt krevende arbeid — ikke en snarvei utenom tenkningen. Systematikk og egne analytiske ferdigheter er ikke motsetninger. De er komplementære krav.

• Skardhamar, Torbjørn (2025). Utsatte områder i Norge? Fulltekst i vitenarkiv
• Andresen, Anette Marie & Skardhamar, Torbjørn (2025). Crime throughout the life course: onset and continuation in offending. Fulltekst i vitenarkiv
• Skardhamar, Torbjørn (2025). Machine learning and risk prediction of violence - theoretical considerations. Fulltekst i vitenarkiv
• Skardhamar, Torbjørn (2025). Hvordan bruke norske registerdata i kriminologisk forskning? Fulltekst i vitenarkiv
• Skardhamar, Torbjørn (2025). Conducting surveys in a hard place. Fulltekst i vitenarkiv
• Skardhamar, Torbjørn (2025). Kriminologisk livsløpsperspektiv. Fulltekst i vitenarkiv
• Skardhamar, Torbjørn (2025). Svenske tilstander_. Fulltekst i vitenarkiv
• Andresen, Anette Marie & Skardhamar, Torbjørn (2025). Age of onset and continued offending. Fulltekst i vitenarkiv Vis sammendrag

  This study aims to provide new evidence of age of onset and the amount of continued offending after onset at different ages. Early onset has been identified as a clear risk-factor for continued offending. Individuals with a later onset is associated with lesser risk for continued offending, but to what degree is uncertain. This uncertainty may be the result of a long standing discussion of whether late or adult onset exists at all. Defining late or adult onset has been proven difficult, where one reason may be the variety data used in the efforts to investigate the phenomenon. This study utilize total population data from Norway to investigate the existence of onset across all ages. We do so in an attempt to overcome some of the challenges in previous studies. The data include official offence data from 1992 to 2020. In this study we explore criminal onset among all full time Norwegian residents above the age of 10 with their first registered charge in 2010. The dataset also allows for descriptive information on continued offending after onset at different ages. The result confirm criminal onset is most common during late teens/early adolescence. Criminal onset, however, occurs in all ages, although less common with the increase in age. Similarly for continued offending, continued offending is most common among earlier onset, but there are instances of quite serious careers at later age of onset.

• Skardhamar, Torbjørn (2025). Life course trajectories vs vriminal career trajectories. Fulltekst i vitenarkiv Vis sammendrag

  Individuals’ offending over time is often described using trajectory modeling, with offending considered as a function of age. This approach follows naturally from a developmental and life course perspective. Alternatively, offending trajectories can be described as a function of time since the onset of offending, thereby avoiding the modeling of criminal careers before any observed offending behavior has begun. In this paper, I demonstrate how these different approaches can lead to diverging results, and argue that chronological age is not always the most relevant time scale. This empirical analysis utilizes total population registry data from Norway.

• Bukten, Anne; Stavseth, Marianne Riksheim; Tverborgvik, Torill; Clausen, Thomas; Lothe, Johan & Havnes, Ingrid Amalia [Vis alle 8 forfattere av denne artikkelen] (2024). Rus og psykisk helse. Fulltekst i vitenarkiv

Se alle arbeider i NVA