Apparently this last year the per capita income of Indians increased to Rs. 46,492 per year. That’s Rs. 3874 ($85) per month. Glory days! The ‘average’ Indian is no longer living in ‘poverty’. But really, per capita income is an average and who cares about the average income when the average Indian hardly exists. The distribution of income is highly skewed and looks like this (see my last related post ‘It’s not a pyramid’). You can see where that places the average.
Yet when we think of an average we make certain assumptions about the spread or distribution of the values that go into this number. If you say the average height of people in India is around 5’ 5” with a standard deviation of 5”, it’s pretty intuitive what that means – that when you arrive in India you will … Read More »
When we enter a space our natural inclination is to do a quick visual survey of who’s around. When we walk into a first grade classroom for instance, we expect to see a whole lot of 5 and 6 year olds and one or two adults.
Now if we were to plot the heights of the people in the room we would get a narrow ‘bell curve’ like distribution centred around 3.5’ and a point or two sticking out somewhere in the range of 5’and 6’.
Let’s say I wasn’t there and all I had in front of me was the distribution that you put down. I could pretty easily guess what kind of situation this was. Where else do you have a bunch of small people with just one large person? Now instead, what if I showed … Read More »
In my last, and much lighter post Who cares about the average income! I talked about the heavy tailed nature of income distributions. Here’s a link to some actual income distributions for the USA, India, Japan and France (scroll all the way to page 3 and look at Figure 1 on that page). Of course, the data for India includes only that of taxpayers and most of India has insufficient income to pay taxes so this is grossly misrepresentative. And unfortunately, the authors also note that the Indian data, even for taxpayers, is incomplete relative to the other countries for the reason that: “In spite of the best of our efforts in collecting the equivalent data from the Income Tax Department of the Government of India or the Reserve Bank of India, we are unable to give … Read More »
Many of us think of statistics as basically taking the average of some numbers. Maybe we even think of the normal distribution or ‘the bell curve’ and the concept of standard deviation. In this context, if you say the average height of people in India is around 5’ 5” with a standard deviation of 5”, it’s pretty intuitive what that means – that when you arrive in India you will find most people around 5’5” with some variation this way and that way of mostly 5”. In large part we all look similar and can fit in the same seats, sleep on the same size beds and fit through the same doorways. Instead, imagine if the distribution was not a bell curve but rather looked like this. A decreasing function with a heavy tail.
What this would mean is that most … Read More »