Millennium Cohort Survey Paper

The Millennium Cohort Study (MCS) is a longitudinal survey conducted by the Centre for Longitudinal Studies that tracks the lives of a sample of about 19,000 babies born in the UK in the year 2000/2001.

The survey is conducted in several waves, with the first one concentrating on the circumstances of the pregnancy and birth as well as the first few months of life.

This first part of the survey also contains important information about the socio-economic background of the family in which the child is born.

The second wave took place when the children were about 3 years old, and the main focus was on continuity and change in the family as well as the parenting environment to extract information about the child 's development. In the third wave in 2006, the children were at the age to start primary school.

The fourth wave took place in 2008.

subsection{The sample} label{subsection:CHILD_Sample} In wave 1, the survey consists of 18,552 children. The effects of sample selection on the size and on the characteristics of our final sample are shown in Table ef{tab:CHILD_SampleSelection} for each step in the selection process, we display the average characteristics which we will use throughout the paper and which will be explained in this section.

First, we exclude 256 twins, since

What remains is a sample of 10,001 observations. Is this sample representative of the initial one? If we compare the average characteristics, we observe some small but significant differences: in particular, we observe that mothers in our final sample are older (30 years old rather than 29), better educated (40\% higher educated versus 33\%), more likely to have had a job during pregnancy (70\% versus 62\%), more likely to be living with their partner (88\% versus 82\%), and slightly richer (weekly equivalent income 342 rather than