It is worth remembering sometimes that, while Scotland has deep-rooted social problems such as communities mired in deprivation, huge health inequalities and in some parts the sort of life expectancy more associated with developing countries, there is also much to celebrate.

Crime is at its lowest level since the 1970s and new research from Edinburgh University shows the conviction rate for young men has fallen by two-thirds in a generation.

While rates have dropped sharply among teenage boys and the under-25s, conviction rates for those over 25 have stayed more or less the same, so the average age at which men in Scotland are convicted of offending has risen from 18 in the late 1980s to 23 today.

The peak age of offending for women has changed even more dramatically, rising from 18 to 30.

This is extremely heartening. It means fewer promising young lives blown off course, fewer troubled souls left stagnating in prison cells and fewer victims of crime.

The question is: why has this happened? While the researchers do not have the answers, it is possible to hazard some informed guesses. There are signs, for instance, that some young people are drinking less, drink being a catalyst for crime. In the Glasgow area, for instance, accident and emergency admissions for underage drinkers fell by about 40 per cent in the five years to 2013.

It has also become more difficult over the last 25 years to break into houses and cars; stealing car stereos and joy-riding used to be typical crimes among young offenders in the 1980s. At the same time it has become harder to cause criminal damage to property such as bus shelters or children's playground equipment because of better, more hardy design. Partly as a consequence of this, vandalism, fire-raising, malicious damage and related crimes have fallen dramatically recently. This means fewer teenagers and young people are being convicted of such crimes and ending up in prisons, sometimes described as "colleges of crime". The youth justice system has also changed, with greater efforts being made to keep teenagers out of prison where possible.

Scotland's Chief Constable Sir Stephen House believes that young people's enthusiastic use of social media, as well as X Box and Playstation, may also be factors in falling youth crime. Playing computer games indoors by definition keeps young people off the streets where they may be more likely to get involved in crime, while social media has become an outlet for outbursts of rage, when in the past such anger would be expressed with spray paint on a bare wall. (Social media can of course be used to make offensive communications, some of which may be criminal, so the benefit is not all one-way.)

Regardless of the reasons, there is no arguing with the statistics. Fewer young people are being convicted of crime. The aim now must be to try and ensure that the rate continues to drop, while policy-makers broaden their attention to older age groups where conviction rates remain stubborn.