Today the media have picked up on claims that the violence on Britain’s streets is a result of women consuming alcohol while pregnant. The story seems to have started with Scotland’s chief medical officer, Dr Harry Burns, reporting the connection to MSPs.

Pre-natal exposure to alcohol is thought to be linked to a wide range of physical and mental defects, including growth deficiency, learning difficulties, epilepsy, and (at a lower level) poor memory and general clumsiness. Children exposed to alcohol in the womb are even reported to have distinctive facial features, narrow eyes and thin upper lips. The name for these phenomena is Foetal Alcohol Spectrum Disorders (FASDs).

The idea that alcohol exposure damages unborn children is perfectly plausible; after all, it clearly damages adults. There’s still a little work to be done to show that alcohol consumption during pregnancy is a significant cause of violent behaviour on the streets of Britain, however, and certainly not enough in the media reports to do so.

The first thing it would be useful to know is whether the explanation being offered is sufficiently powerful. What proportion of pregnant women drink sufficient quantities of alcohol to cause FASDs? What proportion of children whose mothers drink that much alcohol display violent behaviour? How does this compare to the proportion of children whose mothers don’t drink that much alcohol who display violent behaviour?

Without knowing these things, we can’t know how much violent behaviour could be attributed to FASDs if the claim of a causal link were accepted, so can’t assess its importance as a possible cause of anti-social behaviour.

No doubt at least some of this information is out there (even if it didn’t make it into the media reports). However, there was a slightly concerning comment made in The Herald that the only large study of the prevalence of FASDs was in Italy. For a start, Italian drinking habits are rather different to those in Britain, so there has to be some doubt as to whether Italian findings are applicable here. The lack of corroborative studies also raises a doubt as to whether the connection is as well understood as the reports first made it seem.

Before questioning the significance of FASDs as a cause of violence, however, we should question whether they are a cause of violence at all. Assuming that a correlation between pregnant women drinking and their children tending towards violence has been found, how else might this correlation be explained?

One possible explanation would be that women with a disregard for authority are both (a) more likely to disregard medical advice not to drink while pregnant, and (b) more likely to rear children with a disregard for authority (and so with anti-social tendencies). In that case, a mother drinking while pregnant wouldn’t cause her child to be violent; rather, the mother’s drinking and the child’s violence would share a common cause: the mother’s disregard for authority.

There are other theories that could explain the data too. Perhaps living in a rough neighbourhood tends to drive women to drink and to draw children into gangs. Perhaps children who can steal alcohol from their parents are more likely to get drunk and so get involved in fights. Etc, etc.

Of course, there’s a chance that the claimed connection is real and we’re experiencing social problems in Britain because of pregnant women drinking. There’s also a chance that the scientific community has good reason to believe in this connection.

However, the evidence made available in the national press doesn’t show that there’s a correlation between pre-natal alcohol exposure and violent tendencies in this country, doesn’t show that the best explanation of such a correlation would be that pre-natal alcohol exposure causes violent tendencies, and doesn’t show that pre-natal alcohol exposure causing violent tendencies would explain the levels on violence on Britain’s streets.

For these reasons, the information presented in the media falls well short of demonstrating the connection between drinking and violence that is claimed.

Mobile phones have changed our lives. Within a decade or so, mobile phones have gone from rarities to, for many people, necessities; a lot of people now depend on them.

Because of the rapid rise of mobile phones, there was little opportunity to prove them safe before their use became widespread. Concerns remain. One worry is that the radiation emitted by mobile phones might damage the brain. Another is that it might have a negative impact on fertility.

A correlation has now been found between the amount of time that men spend using phones and reduced fertility. A study in Ohio found that men who use phones for four or more hours per day have fewer and lower quality sperm than men who use phones for between two and four hours per day, who in turn have fewer and lower quality sperm than men who use phones still less. Men who do not use mobile phones at all were found to be the most fertile of all.

The conclusion drawn by the scientists in Ohio was that mobile phone use does seem to damage fertility. However, a BBC article on the subject included the views of Dr Allan Pacey, who was more cautious in his response to the data.

Most of the concerns about mobile phone use damaging fertility relate to the use of hands-free kits. These allow people to leave their phones in their pockets while using their phones, meaning that some of the radiation emitted by the phone is absorbed by the testes.

As Dr Pacey pointed out, though, the men studied in the survey were not using hands-free kits. It is therefore unclear how mobile phone use could damage their fertility.

Dr Pacey suggested several alternative explanations of the data: men who use mobile phones a lot might tend to lead more sedantry lives, or be more stressed, or have poorer diets, each of which might in turn affect fertility.

If any of these is the correct explanation of the data, then there is no direct causal connection between mobile phone use and reduced fertility. Dr Pacey’s point is that mere correlation does not prove causation; to be sure that using a mobile phone can damage men’s fertility, we would need to have a clearer idea of the causal mechanism by which the damage might be done.

Back in May 2002, the BBC ran a story affirming that breast-milk boosts babies’ brainpower. The central claim of the article was this: “The longer a baby is breast-fed the more intelligent it is likely to be.”

This claim was supported by a statistical analysis. Danish and American researchers had recorded how individuals were fed as babies, measured their IQs as adults, and found a connection.

Statistically, babies that were breast-fed for less than a month had below-average IQs. IQ increased proportionally to how long babies were breast-fed up to nine months, after which it tapered off.

On this basis, the conclusion was drawn: breast-feeding for the first nine-months of a baby’s life increases its intelligence.

Four years later, the flaw in this reasoning has been spotted, and a new story has been run. This time the headline is “Breast Milk does not Boost IQ”.

The more recent article explains that the breast-fed babies are not more intelligent because they are breast-fed, but because breast-feeding mothers tend to be more intelligent, educated, and affluent. These qualities are passed on to the children through genetic and other means, but there is no evidence to indicate that they are passed on by breast-feeding.

In other words, the original study committed the correlation not causation fallacy, mistaking a statistical correlation for a causal link.