International Journal on Criminology Volume 1, Number 1, Fall 2013 | Page 41

International Journal on Criminology
previous year. This is, therefore, a simple ratio, which for certain offenses may be greater
than 100.
Relating, in a mathematical sense, one quantity (A) to another (B) is one of the first
stages of analysis. The meaning of the operation will obviously depend on the types of
quantities.
4. The stories of cohorts
COHORT: A cohort is any group of persons who experience the same event within a
given time frame, usually a calendar year. Demography's traditional cohorts (cohorts of
births, of generations, or of deaths, etc.) give way to cohorts of individuals committed to
prison or detained, cohorts of persons benefiting from a release, etc. Whether it involves
observation over time (e.g., observation of cohorts of people committed to prison) or
retrospective analysis (e.g., of cohorts of those released), the value of this kind of
approach can be explained in this way: “The fact is that biographical events do not occur
according to clear groups, only to be lost in a mass of statistics. On the contrary, these
events are submitted to the analyst as individual stories, which allow for particularly rich
analyses due to the network of connections that can be brought out between the different
types of events at play.” 6 Even if this approach is not the prerogative of demographers, it
has greatly contributed to the visibility of our way of understanding the correctional field.
In our work, analyses of cohorts have primarily focused on the three following areas,
which are more or less interwoven: the study of incarceration trends and trajectories and
the lengths of time spent in prison, early release and alternative sanctions and finally, the
issue of “recidivism.”
LONGITUDINAL ANALYSIS: This expression is synonymous with analysis by
cohort. Observations over time (prospective analysis) and retrospective analysis are the
two main methods employed to collect longitudinal data. It is fundamentally different
from cross-sectional analysis. 7
RETROSPECTIVE COHORT ANALYSIS: As its title indicates, retrospective cohort
analysis is a return to the past. Here is an example: to study changes and trends in early
release decisions, we use cohorts of inmates freed during a certain period, and we
examine, retrospectively, the decisions that affected them throughout their time in
prison—convictions, credits toward reduced sentences, possible withdrawal of those
reduced sentences after particular incidents, anticipated conditions of release, etc. We are
thus able to reconstitute a history of the time in prison.
In this type of research, the study of modified sentences and early releases are usually
combined with the study of “recidivism.” 8 The retrospective analysis of what occurred
before release (during the time in prison, or even before that period) includes the
observation over time of what occurs afterwards (new cases).
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6 R. Pressat, Dictionnaire de démographie (Paris: PUF, 1979).
7 Pierre V. Tournier, “Note technique sur le diagramme de Lexis,” in Travaux & Documents, 2
(Paris: Direction de l'administration pénitentiaire, 1980).
8 A. Kensey and Pierre V. Tournier. “Prisonniers du passé? Cohorte des personnes condamnées
libérées en 1996–1997: examen de leur casier judiciaire 5 ans après la levée d’écrou (échantillon
national aléatoire stratifié selon l’infraction),” in Travaux & Documents, 68 (Paris: Direction de
l’administration pénitentiaire, 2005).
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