Friday, 26 August 2011

Obesity: Why is the prevalence so high?

It has been reported today that approximately half of men and forty per-cent of women in the UK could be obese by 2030. This is undesirable not only for the individuals concerned, who will be at increased risk of obesity-related morbidity and mortality, but also for society, which must cover the cost of medical care for these people. If this situation is to be avoided, and if the current prevalence of obesity is to be reduced, action and interventions must address the range of factors that contribute to obesity.

'Obesogenic' environment
Becoming obese or overweight isn't simply a matter of a failure to exercise personal responsibility or restraint. Of course, these things are very important but they do not tell the whole story. The truth is that we live in what has been called an 'obesogenic' environment, in which it is highly likely that people will consume a diet that promotes weight gain unless they are armed with adequate knowledge of nutrition and healthy eating. The supermarket, now the main source of food for most people, is an excellent example of this. Somewhere in supermarkets, amongst the crisps, chocolates, sweets, biscuits, fizzy drinks, processed meats, frozen pizzas, pies, ready meals, cakes, alcoholic drinks, and other unhealthy products, there are in fact some healthy options. But for those who have no real understanding of what is healthy and what isn't, it's quite easy to leave with trolley loads of food and drink that will make them and their families fat and unhealthy.

In addition to supermarkets, there is a multitude of outlets selling food and drink at all hours of the day and night for those feeling hungry while on the move. There are junk food chains, fried chicken shops, chip shops, sandwich, coffee, and cake shops, pubs and bars, and so on. You might even be 'lucky' enough to have vending machines in your workplace or someone from the local sandwich shop coming in to sell you fat sandwiches and cakes. There are some healthy options in these kinds of places, but they are almost always outweighed massively by high-calorie options that are full of sugar and/or fat. Unless someone has the nutritional knowledge to identify the healthy options, the chances are that they'll choose something else.

To illustrate how someone could easily consume way over their recommended caloric intake, consider the following hypothetical example of an office worker in London. They wake up late and skip breakfast. Feeling hungry at the train station, they grab a chocolate bar from the kiosk. By mid-morning at work they are feeling more hungry, so they nip across to Starbuck's for a blueberry muffin and a Caffe Mocha. At lunch, they go with their team to the local Wetherspoon's for a pub lunch - they order the scampi and chips. After a long afternoon at work and having worked late, they grab a Big Mac, medium fries, and medium banana milkshake from McDonald's on their way home. Laid out on a table, that wouldn't look like a lot of food. Nevertheless, it contains 3,300 calories. For a man, that's 800 over the recommended daily caloric intake. Similar examples could be given with foods from other outlets or foods from supermarkets.

In addition to the wide availability of cheap, readily available foods that are high in calories, fat, and sugar, there are other aspects of the modern environment and lifestyle that promote weight gain. Most people have highly sedentary jobs, for which stapling two pieces of paper together or picking up a phone would be among the most physically demanding aspects. People no longer walk significant distances these days either - in the time-pressured lifestyle people are forced to adopt today, they are driving everywhere or getting public transport. The huge amounts of money that companies spend on advertising junk foods can also not be ignored. The reason that these companies spend so much on advertising is because advertising works.

Poor knowledge of nutrition and physical exercise
In addition to existing in the previously described environment, most people simply have no knowledge of nutrition or how to exercise for health and fitness. They do not possess this knowledge because they've never been taught it and have either been too lazy to learn it of their own volition or have tried but been fooled or deterred by the huge amount of myth and contradictory information/disinformation that exists on these subjects on the internet and in the media.

Kids leave school with detailed knowledge of many topics irrelevant to their lives. They can calculate angles within a triangle or talk about people or events from hundreds of years ago, but they don't have the knowledge required to ensure that their own eating behaviour is good for their health. And while they've learned the rules of games like basketball and cricket in PE, they have no awareness of how to actually plan an effective and healthy workout or routine.

Given this mixture of 'obesogenic' environment and widespread ignorance of how to avoid its pernicious effects, it is not surprising that so many people are overweight or obese.

Other issues
Of course, the blame doesn't just lie with the companies promoting and selling unhealthy food, or the educational system that doesn't teach people how to maintain a healthy body and lifestyle. People who are overweight or obese must take some responsibility too. Most people have a general awareness of what food is "good" (or healthy) and what food is "bad" (or unhealthy). They know, for example, that oatmeal for breakfast is better for them than a Mars Bar, even if they can't explain why. They also know that big slabs of chocolate or boxes of cakes are bad for them, even if they are 'buy one get one free' at the supermarket.

Many people also see food as a source of pleasure rather than a source of nutrients for the body. Everything they eat has to taste great and eating must always be a pleasurable experience. If it doesn't taste great, they're not interested in eating it. These people are just like the little boy who wont eat his vegetables because they are 'disgusting'. It is within their power to not behave like spoiled children.

There is also a mentality that values quantity over quality. Many people will choose to buy greater quantities of cheap, poor quality foods than smaller quantities of more expensive, higher quality foods. While more economical in the sense that they get more for their money, it is a practice which is likely to encourage weight gain.

The role of biological abnormalities and deep-seated psychological problems in the most extreme cases of obesity should also not be ignored.

Because of the broad range of factors contributing to the increasing prevalence of obesity, no single type of action or intervention is going to solve the problem. Simplistic health promotion messages merely telling people to eat more healthily will be met with extremely limited success. Research in health psychology has shown that these kinds of interventions are not particularly successful. The reason for this is probably that instrumental information (e.g. vegetables are good for my health) are not always the most important predictor of behavioural intentions and that behavioural intentions are often not a strong predictor of actual behaviour.

More comprehensive and detailed health education in schools would be more likely to be effective. The wide availability of cheap and readily available junk foods would still be a serious problem, however. Like it or not, health protective measures have to be taken which would either reduce the availability and advertisement of these products, or make it more difficult for people to afford them. That we live in a society in which McDonald's can sponsor youth football or sporting events such as the Olympics indicates that something is deeply wrong and that action is needed to limit the effects of such organisations on population health.

Sunday, 14 August 2011

Was David Starkey's argument on Newsnight racist?

Having watched David Starkey’s appearance on Newsnight, I’m not at all surprised that people have reacted with outrage… as they seemingly do in response to everything these days. Rather than carefully considering his comments and ensuring that they’ve accurately interpreted the point he was making, they’ve heard the words “black” and “white” and cried “racism”.

While I concede that Starkey didn’t articulate his argument well – mostly his own fault, but partly the fault of the others for interrupting him – I feel that it was perfectly discernible (though still not necessarily correct) given a little thought. His argument was that there is a particular black subculture which some white people have now adopted, and that the values of this subculture might have played a role in the recent riots. Perhaps I’m giving him the benefit of the doubt, but I really did not perceive that he was arguing that there is a unitary “black culture” to which all black people belong and that this culture is violent.

His argument (at least as I have perceived it) is not a racist one. A racist argument would be that black people inherently have a greater propensity to commit violent crime. He did not make such an argument, or anything like it. The view that most black people are decent, non-violent, and law-abiding is perfectly compatible with his view that there is a particular subculture (which is traditionally black, but to which most black people do not belong) that has destructive values.

Aside from twisting some of his words to portray them as racist, some people have ignored his other comments on the programme which showed that he wasn’t making an argument from race at all. For example, he said “it’s not skin colour, it’s cultural”. He also said that Enoch Powell was “completely wrong” about inter-communal violence, which is the opposite view to the BNP who have been portraying the recent riots as “race riots”.

It is quite sad to see people calling for the end to someone’s career and livelihood on the basis of a misinterpretation.  People like Owen Jones (who was on the show too) seem concerned that Starkey has “opened a floodgate of racism”, but if others misperceive his argument to be about race, then they are merely making the same mistake as Jones himself.

The real question people should be asking is whether Starkey was right to implicate the particular subculture he was referring to as having an important role in the recent riots. 

Saturday, 13 August 2011

Riots in England: Conflating Correlation with Causation

It is an elementary point in statistics that it is not wise to infer causation from correlation. While it might appear that two variables have a causal relationship, it is possible that they do not. An example commonly used to illustrate this point is:

As ice cream sales increase, so does the rate of deaths from drowning.
Therefore ice cream causes drowning.

This reasoning ignores the mediating variable, i.e. good weather, which actually explains both the increase in ice cream sales and the increase in rate of deaths from drowning. This is a simple example that is used to make a point.

After the recent riots in London and other English cities, most on the left are attributing the events to "deprivation". Some have mapped the location of the riots on top of deprivation data (only including London, for some reason), observed a pattern, and decided that it's case closed. Not so fast! What pattern would be observed if we were to look at the relationship between other variables and rioting areas? I'm going to use population density and proportion of area that is non-white here, because they are variables that the left will not want to consider.

Table 1 depicts the 40 highest ranking Local Authorities for each of the following measures, separately: average LSOA score on Indices of Deprivation 2010, population density, and proportion of population that is non-white. The Local Authorities in bold font are those for which I was able to find evidence of rioting having taken place. The table quite clearly indicates that if someone wanted to pick a variable and claim it as an explanation, they'd chose population density or proportion of population that is non-white, and not deprivation. Not only do more of the LAs where rioting took place rank highly on these variables, they seemingly account for those areas which were considered surprising from the deprivation perspective. For example, while Croydon and Ealing are right up there on these measures, they're not high on the deprivation index (107 and 80, respectively).

Of course, the left wouldn't even entertain the idea that these variables might have some explanatory value. They dismiss them out-of-hand, as they're not interested in anything which would lead to arguments against over-population or immigration. They are ideologically obsessed with equality, and they will always perceive events in this context. That they're so impressed by misleading maps simply plotting one variable against another demonstrates that they're not at all practiced in arguing from evidence. Take this entry on the Greek Left Review blog as an example.

In summary, the purpose of this post is to highlight that inferring causation from correlation is not a sensible practice and that variables other than deprivation can be used in a similarly simplistic fashion to 'prove' entirely different arguments.

Thursday, 11 August 2011

The dishonest Indices of Deprivation map doing the rounds

There is a map doing the rounds which is said to depict level of deprivation and areas where riots took place. This map has seemingly impressed many people and has been tweeted and re-tweeted all over Twitter. It can be seen here.

As someone who has spent a number of years working in statistics and research at the Office for National Statistics, I'm disappointed in this map. I'm disappointed because it represents either a deliberate attempt to mislead, or an ignorance of how to fairly and properly display data. The reason that this map is misleading is because it depicts deprivation for London only. People looking at this could be forgiven for looking upon the map as incontrovertible evidence that deprivation leads to the kind of behaviour that occurred. However, if the data had been displayed for the rest of England, it would be quite apparent that the association between deprivation and rioting is actually quite weak. Failing to map the data in its entirety removes the need for an explanation of why a few deprived areas got involved in the riots, but most deprived areas did not. 

I can only speculate on why someone would go to the effort to produce their own map when a perfectly useful one is made available by the Department for Communities and Local Government, who produce the Indices of Deprivation. This map can be seen below and can be found, along with methodological information in this document.

This map quite clearly depicts high levels of deprivation in many regions of the country. Most of these were not affected by rioting. For example, there was no rioting in the North East. I would recommend looking at the actual data, as it carries a much greater level of detail than a map. For example, from the map above it isn't apparent that the most deprived Lower Layer Super Output Area (LSOA) in England is in Tendring, Essex, or that no LSOA in London is within the most deprived 400 in the country. I talk about this data more in a previous blog entry.

Ultimately, excluding items from analysis because they don't show what you want to see is not just bad practice, but it is dishonest. Statistics such as these are created at considerable expense with the purpose of informing policy, not for people to bastardise them in order to support their pre-existing opinions and beliefs. At the very best, the map in question indicates that there were riots in some deprived areas in London. That's it - that's all it does. It doesn't prove that deprivation was an important causal factor. The data as a whole indicates that it isn't actually an important factor at all. This is consistent with what we know about people who aren't financially wealthy - most of them are decent, moral people who wouldn't commit such criminal and immoral acts.

Wednesday, 10 August 2011

UK Riots: Is 'deprivation' an adequate explanation?

Since the recent riots kicked off, there has been a considerable amount of political opportunism: Ken Livingstone jumped on the troubles as a vehicle for promoting his 2012 Mayoral election campaign; the BNP have been busily promoting the view that the events can be explained by and are a consequence of immigration and racial diversity, and various leftist and socialist types have attempted to attribute the events to “cuts” and “deprivation” in order to attack the current government and to argue for a statist position.

Sadly, people tend to react to events like this in a knee-jerk fashion that is consistent with their own personal prejudices. While the BNP apparently can’t see the white faces of many of the rioters, the deprivation brigade apparently can’t acknowledge that the riots were organised on expensive gadgets that genuinely deprived people wouldn't own. The view promoted by the latter group is difficult to reconcile with the wealth of statistical information that exists on indicators relating to deprivation, and that shall be the topic of this post. 

Indices of Deprivation

The Department of Communities and Local Government produces a measurement of deprivation (for England) at the small area level based on 38 indicators across seven domains (Income Deprivation, Employment Deprivation, Health Deprivation and Disability, Education Skills and Training Deprivation, Barriers to Housing and Services, Living Environment Deprivation, and Crime). Looking at this data at either the Local Authority (LA) or Lower Layer Super Output Area (LSOA) casts doubt on the view that deprivation is a crucial factor in the riots.

Table 1 shows the rank of average LSOA score for those LAs in which there has been rioting. The first thing that must be conceded is that areas like Liverpool and Hackney are at the very top end of most deprived areas, and the rest (excluding Gloucester) are within the top 25%. But, there were no riots in Knowsley (5th), Blackpool (6th), Middlesbrough (8th) or most of the other ranks between 1 and 125 not included in Table 1.

There are various ways to look at this data by LA. Another is to calculate the proportion of LSOAs within an LA that are in the top 10% of most deprived LSOAs in England. This measure provides an idea of the proportion of an LA that is amongst the most deprived in the country. The top five (in descending order of proportion) are Liverpool, Middlesbrough, Manchester, Knowsley, and Kingston upon Hull. Riots failed to break out in three of these.

Should one be concerned that perhaps the detail is being lost at the LA level and feel that looking at each of the 32,482 LSOAs would reveal that it was actually the most deprived small areas that the riots occurred in, a quick look at the data will alleviate that concern. There is not one London LSOA within the top 400 most deprived, many of which are in LAs where there was no trouble, e.g. Blackpool, Burnley, Middlesbrough, Newcastle upon Tyne, Bradford, etc. The most deprived LSOA according to this measure is in Tendring, Essex. 

Those arguing that this is all about deprivation have the difficult task of explaining precisely why it is that deprivation should cause riots in places like London and Manchester but not elsewhere. 


Unemployment appears to be one of the most common deprivation-related factors that is mentioned as a cause. In a previous post I explained that there are many other areas around the country with high levels of unemployment to which trouble did not spread. For example, despite having an unemployment rate of 10.7% compared to Haringey’s 8.9%, it wasn’t all kicking off down in Canterbury. Nor was there trouble in Glasgow (12.4%) or most areas with high rates of unemployment.

It is also instructive to look at unemployment over time within some of the areas affected by the riots. 

Contrary to reactionary alarmism that unemployment would rocket under the current government, it can be seen in Figure 1 that the national rate actually hasn’t increased since the increase that occurred at the end of the previous government. Indeed, the most recent statistical bulletin on unemployment from the Office for National Statistics has the rate at 7.7% for the three months to May 2011. It can also be seen that the unemployment rate in Croydon and Haringey has actually decreased since the last General Election and the unemployment rate in Hackney is less than it was back in 2007. Surely if this was about unemployment, the residents of those areas should have been going ballistic in recent years. Alas, they have not.

Alternative explanations

The way in which these riots started is perhaps the easiest part to explain. There is a history of tension between the police and some elements of the black community. An incident occurred which sparked an angry reaction from that community. It is more difficult to account for the manner in which it spread beyond this to other areas and in particular why it spread to some areas and not others.

Criminal opportunism undoubtedly played a significant role. The initially weak response from the police created the impression that people could loot and vandalise with impunity. Once some tough talk and a little bit of tough action was issued, it has all seemed to have quietened down. Contrary to socialistic idealism, there will always be a criminal element within society which will commit criminal acts if they think they can get away with it. We have a criminal justice system and a police force for this reason.

The deprivation argument is really quite weak. The statistical evidence doesn’t support it, and what we’ve seen and heard in the media coverage doesn’t support it. People organising violence, vandalism, theft, and arson, on smart phones and the internet are not deprived. Only according to the dubious concept of “relative deprivation” can they possibly be said to be deprived. Most people can live peacefully in the knowledge than many others out there are more wealthy, have nicer houses, better and faster cars, and possessions that we can’t afford. That this sort of “deprivation” could be considered a legitimate reason for such criminality perhaps indicates some of the deeper problems with values in society that could encourage people to behave in this way.  

Monday, 8 August 2011

London Riots: Is unemployment and deprivation really to blame?

Having followed the coverage of, and response to, the “London Riots” over the last few days, I’ve noticed that some are using factors such as unemployment to explain away the behaviour of the perpetrators. This alone is not a satisfactory explanation. The vast number of people in this country who suffer from unemployment and economic deprivation and who do not resort to criminal behaviour - of any type, let alone involvement in mass violence, vandalism, and theft – demonstrate that criminality does not follow necessarily from deprivation.

Further to this, labour market statistics from the Office for National Statistics reveal that there are other areas around the country with higher rates of unemployment and higher rates of Jobseekers’ Allowance (JSA) claimants than Haringey (the Local Authority in which Tottenham is located and this trouble originated). I’ve provided the statistics for these areas and Haringey in the table below:

The obvious question arising from this data is that if this is all about unemployment and lack of opportunity, why are we not seeing similar behaviour in all areas worse afflicted by such deprivation? A more awkward and inconvenient question is why is the behaviour spreading from Tottenham to areas like Hackney and Brixton, but not to places like Liverpool or Hartlepool?

Clearly economic deprivation is neither a necessary nor sufficient condition for such criminal behaviour. It is not necessary as people can riot and protest for entirely different reasons and it is not sufficient as it rarely leads to rioting. To argue that this is all about economic deprivation is to ignore other possible factors, absolve the perpetrators of guilt, and diminish the seriousness of their behaviour. If indeed deprivation is their concern (which I don't concede it is), they'd have decided to react to difficult times in a way that the vast majority of others in similar conditions have not and would not, and that is their responsibility. They are thugs and criminals with no respect whatsoever for the property, livelihoods, and welfare of others. 

Thursday, 4 August 2011

The Capital Punishment e-petition

The way in which some people have been reacting to today's news regarding an e-petition for the restoration of capital punishment for murderers of children and on-duty police officers would make anyone think that its restoration is certain and imminent. It is not. The FAQ on the e-petitions website states that if an e-petition receives 100,000 signatures it will be "eligible" for a debate in the House of Commons. As I type this, the e-petition has a mere 725 signatures. If it receives 100,000 signatures (which seems an inappropriately low number at just 0.16% of the population - public demonstrations involving larger numbers have been ignored) there might be a debate. That is essentially the extent of this situation.

I'm not particularly fond of the idea of capital punishment. It seems inherently wrong for the state to terminate someone's existence. However, there are some crimes that are so heinous that the only other appropriate punishment would be imprisonment for life. For example, those who have raped/killed children can surely never be released into the public because of the possibility of their re-offending and the terrible consequences that would entail.