Although Nielsen is an good place to launch an analytics or marketing research career, the company provides few incentives to stay with the company. As such, the vast majority of talented employees leave the company after 3 or 4 years, especially in departments such as sales forecasting (BASES) and Mixed Market Modeling (Custom Analytics). The reasons for this high turnover include weak onboarding process, difficulty moving around within the company, the technical nature of the work, poor work/life balance, and insufficient compensation. My examples below will primarily address the forecasting branch of Nielsen.
Onboarding
Although Nielsen has made good gains in terms of training new hires, the adjustment to work is still very rough. The current best practice includes giving a new analyst a large project, preferably one that requres concept and product analysis, a project that takes over a month to complete. This means that most people work long hours to complete the first project and learn quickly, while a meaningful minority do not catch on quick enough and are usually let go within the first year or two.
Moving within the Company
Although some individuals are able to move from department to department, most find this challenging. In order to move, you need to prove that 1) you are valuable enough to stay with the company but 2) not too valuable that your manager doesn't want to you to leave the team. Often people leave the company because they are not able to get out of their current department to a different part of Nielsen.
Technical Work
The work that Nielsen does can be quite exacting and detail oriented. Some leave simply because they don't like marketing research, forecasting or analysis.
Work/Life Balance
As with any project-based supplier, the Nielsen forecasting department has difficulties keeping a good work/life balance. If you are assigned a large project, you have to simply work hard until it is completed. This can mean working 60+ hours per week when things are busy. If you have firm commitments in the evenings and need a definite 8-5 job, this is probably not a good fit for you.
Insufficient Compensation
Nielsen salaries are competitive for new college hires, but pay increases are meager as you spend time working for the company. At the same time, the experience that you get an Nielsen is quite valuable. A number of my coworkers leave Nielsen after three or four years because they can take a 25% pay increase to work somewhere else. Nielsen currently does not have a strong compensation program to keep talented individuals at the company, especially when they have been at Nielsen for over three years.