To answer our research question, we analyze data that were made available by the Research and Documentation Centre (WODC) of The Netherlands Ministry of Justice. The data stem from the General Documentation Files (GDF) of the Criminal Record Office (‘rapsheets’) and contain information on every criminal case registered by the police at the Public Prosecutor’s Office of all 153,252 offenders convicted in 1997, of which 16,561 where sentenced to community service and 15,797 to imprisonment.
Recorded conviction careers of all offenders sentenced in 1997 were reconstructed using abstracts from the GDF as available in 2005. Consequently, the data include the entire officially recorded criminal history, i.e. the number of convictions per year, starting at age 12 up to the year 2005.Footnote 7 Entries in the GDF include all criminal cases that have led to any type of judicial action. However, in this study, we only use information on those offenses that were either followed by a conviction or a prosecutorial disposition due to policy reasons, thereby excluding offenses that resulted in an acquittal or a prosecutorial disposition due to insufficient evidence.
Next to criminal career information, the GDF data contains information on other, known as confounding variables, such as sex, age, nationality, type of index offense, number of crimes in case of conviction, and severity of the offense. The GDF also contain information on the length of community service and the length of imprisonment following a conviction. This extra information is used to control for selection effects.
The overall sample size is reduced for comparison for various reasons. First, our analysis focuses on offenders aged between 18 and 50 years. We, therefore, exclude 6,340 offenders aged younger than 18 and older than 50.Footnote 8 Second, offenders sentenced to either community service or imprisonment prior to their conviction in 1997 were excluded to prevent interference from feed-back effects (n = 12,698). Feed-back effects would imply a prior sanction to affect both the chances of a subsequent community service and imprisonment as well as post-sanction recidivism. Third, considering the official rule stated in the Criminal Code applicable in 1997 that community service could replace imprisonment of maximally six months, offenders first imprisoned longer than six months were also excluded (n = 1,972). Finally, those offenders sentenced to both community service and imprisonment in 1997 were excluded (n = 40). These restrictions resulted in an analysis sample of 11,308 offenders, of which 7,806 were sentenced to community service and 3,502 to imprisonment. All sentences involving detention, including being placed in a reformatory school, of maximally six months were counted as imprisonment.Footnote 9
The outcome variable in our study is the post-treatment conviction rate. All convictions after the index offense are measured as recidivism, even when these subsequent convictions took place in 1997. The index offense was defined as an offender’s first 1997 conviction that led to either community service or imprisonment. Since we have data up to 2005, our follow-up period spans a maximum of eight years.
When applicable, in constructing our outcome variable, we control for the duration of incapacitation by multiplying the observed number of convictions by the inverse of the proportion of the follow-up period offenders were actually free to offend. We thereby assume that offenders would have been convicted at the same rate for the entire period if they had not been imprisoned.
Variables used in the matching procedures
When comparing two types of criminal justice interventions the list of potential confounding variables is endless. Nagin et al. (2009) state that to reach an acceptable base of comparison between groups two case characteristic variables—criminal history and conviction offense type—and three demographic variables—age, race, and sex— shoulddefinitely be accounted for. Our model includes these variables and adds even more.
To take case characteristics into account, we include 18 dummies representing offense types of the index offense (see Table 1). A continuous variable indicating the severity of the offense based on the maximum penalty is also included in the model (ranging from 0 to 20). Next, the number of crimes in case of conviction in 1997 was added to the model. Furthermore, we take into account the criminal history in great detail. In total, six variables are included concerning the criminal history of offenders. Distinctions are made between property crimes, violent crimes, and other crimes, and between the criminal history in the year prior to the index offense and the past ten years.
To take the demographic background into account, age (divided by ten) is added to our model as a continuous variable and quadratic to allow for a non-linear relationship between age and the chance of community service. Our model also includes dummy variables indicating whether the offender was male or female and whether the offender was born in The Netherlands or not.
In addition, prior to matching on propensity scores we match by different age categories, sex, and sentence-length. For the matching by variable, we distinguish seven age-categories.Footnote 10 For the length of the sentence, we distinguish six categories, by which the classification of community service and imprisonment follows article 22b of the Criminal Code at which community service up to 60 hours can replace one month imprisonment (Schuyt 2008). The first category thus includes community service up to 60 hours and prison sentences up to one month. Subsequent categories for community service are chosen at a smaller range so that the maximum of 240 hours is not exceeded.Footnote 11 We match by sentence length to prevent comparing offenders having preformed a minimum amount (e.g., 40 hours) of community service to offenders having served a maximum amount (e.g., 6 months) of imprisonment.
Table 1 presents descriptive information on the variables included in analyses. A naïve comparison of recidivism rates shows that one year after community service, offenders recidivate on average 0.25 times, and one year after imprisonment, offenders recidivate on average 0.65 times. During a follow-up of eight years offenders recidivate on average 1.70 times after community service and 3.33 times after imprisonment. The mean age of those offenders sentenced to community service was 30.1 and 28.9 years for the imprisoned group (Table 1). Furthermore, of the offenders sentenced to community service, 18.3% were female and 32.1% were non-native, whereas of the imprisoned, 12.2% were female and 68.6% were non-native. Also, in 1997, at the moment of conviction for the index offense, the offenders sentenced to community sentence had on average 0.81 offenses in their criminal history (measured back to 1987) and the imprisoned group had on average 0.90 prior offenses.Footnote 12 The length of community service varied from 1 to 240 hours, with a mean length of 106 hours, whereas the length of the imprisonment varied from one day to six months with a mean of 60.3 days. The distribution of the length of imprisonment is skewed—half of the imprisoned had a sentence up to two months. The number of offenders sentenced to longer imprisonment than two months is remarkably lower. This again underlines that the results of our analyses should not be generalized to the entire population of imprisoned. They apply only to those sentenced to short-term imprisonment (but see footnote 9).