Smrithi Sunil - India In Data

In April 2023 India overtook China to become the most populous country in the world. Represented as a single data point on the world map, India is diverse in complex ways. Geography, language, and culture, are just a few dimensions that make India diverse. In April 2024 I started to dig into that single number, 1.4 billion - Who are we? Where do we live? How healthy are we? How have we changed over time? and What can we learn from the past?

I wanted to break down that single number on the world map. Welcome to India in Data! This will be a series of posts where I explore data on India and provide my inexperienced insights. I figured I could use data to expand my understanding of India. I love looking at data and using data to learn about the world. As an engineer and neuroscientist, I collect, visualize, analyze, and interpret data on a daily basis. While I will not be collecting any of my own data, I will use the wealth of data that is publicly available and make visualizations that are more accessible than tables in PDF format. Perhaps it might even be interesting to someone who is not me.

Population over time

In this post I touch on some general population trends and characteristics. Below is an interactive map and line graph of population by state over time¹. Nothing too unusual here, the population of every state has been increasing over time. Note that 2011 is the most recent census year. The census was not conducted in 2021 due to COVID-19 and will be held after the 2024 general election. Note: Explore the line plot further by individually selecting specific states or a subset of states.

Uttar Pradesh is by far the most populous state and has been since 1901 at least. Uttar Pradesh is followed by Maharashtra, Bihar, and West Bengal. Sikkim is the least populous state.

Sex ratio over time

The ratio between number of males and females in the population is called the sex ratio. A number of different factors, like birth ratio, death ratio, and migration can affect the overall population sex ratio of a given place. The natural sex ratio at birth is slightly biased towards more males being born. This trend is seen in almost every country, and on average, there are 105 males born for every 100 females (explore the world data at Our World in Data²). Following birth, at virtually every age group, more males die compared to females. Additionally, women tend to live longer than men. These last two factors contribute to a larger share of the population being female in the later years. In 2021, this crossover point for the world was around 50 years of age. Below is an interactive map and line graph of the number of females for every 100 males across states over time.

These graphs are a little depressing to look at. India has a highly skewed sex ratio. Over time, the ratio becomes more skewed towards males in most states. Overlaid on the line plot is the natural sex ratio at birth in solid black. The translucent black dots represent India’s mean sex ratio. While the distribution across states is large, the mean ratio dips below the natural birth ratio in the 1971 data. A siginificant factor that might play a role in this change is the use of ultrasound technology to perform sex selective abortions. Ultrasound was introduced in India in the 60s and became widely available in the 70s. While having access to ultrasound in pregnancy is a good thing for maternal and child outcomes, it resulted in a large increase in sex selective abortions. India passed the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act in 1994 which banned prenatal sex determintaion. The trending upward mean sex ratio post 2000 might be a result of the PCPNDT Act.

However, as mentioned, the distribution across states is large and the birth ratio is not the only factor that affects the sex ratio. Take for example Kerala. Kerala tends to be skewed towards more females throughout the years. Many factors might contribute to this trend. Historically, Kerala was a matrelineal society where the family assets were passed down to the children of the daughters. This made women key decision makers in the family. While this system is no longer formally practiced, it might have had a lasting cultural impact within Kerala in a country that otherwise has a strong ‘son preference’. Additionally, Kerala has a high literacy rate, especially female literacy, and a strong public health system. This might contribute to low sex selective abortion as well as longer life expectancy and generally women live longer than men. Another factor seen in recent years might be the high rate of emigration from Kerala to the Middle East. Emigration tends to be skewed towards men and might contribute to Kerala’s sex ratio. All these factors taken together might explain the high (and climbing) female to male sex ratio in Kerala.

On the other end of the spectrum, Delhi has the lowest female to male sex ratio. Delhi is a large urban center with a high rate of migration into the capital, which again, probably tends to be male skewed. The lowest points appear to be around the time of the independence struggle, although even the last few decades indicate significant gender imbalances. Delhi is surrounded by Uttar Pradesh and Haryana, both states that have a history of male preference and might influence the sex ratio in Delhi.

I will explore sex ratio in more detail in a future post.

Age breakdown in 2011

The age distribution of a population is another important dempgraphic factor that can provide insights into the health, social, and economic characteristics of a place. Below is a bar plot of India’s population broken down by age range and a map with the median age for each state³. India is a relatively young country with the northern half of the country being generally younger than the southern half. Fertility rate and life expectancy are two possible factors that play a role in the age distribution. I expect these to correlate across states in a similar way and will be explored in a later post.

Conclusion

Welcome to India In Data and thanks for making it this far.

As of May 2024 India is the most populous country and accounts for over 17% of the world’s population.

The sex ratio in India is highly skewed towards males. In 2011 every state except Kerala had more males than females.

India is a young country with the northern half of the country being generally younger than the southern half.

All the data used in this post and corresponding code can be found on my github page.⁴

Footnotes

Data source: Census of India. Decadal Variation in Population 1901-2011.↩︎
Hannah Ritchie and Max Roser (2019) - “Gender Ratio” Published online at OurWorldInData.org. Retrieved from: ‘https://ourworldindata.org/gender-ratio’ [Online Resource]↩︎
Data source: Census of India. Population Projections for India and States 2011-2036.↩︎
Smrithi’s Github ↩︎