Methodology, scope and principles An assessment was made of the selected themes to see whether quantifying them is feasible with the available data and the defined parameters for the valuation. If not (e.g. diversity), the theme is included qualitatively. This is an evaluation of the social costs and benefits that are not covered in the financial results. The evaluation uses external (academic) studies as well as our own data.Scope: The impact analysis focuses exclusively on the activities of NS in the Netherlands, which are included as fully as possible.Reference for the methodology and scope: For a detailed description of the methodology and scope for each theme, please see www.ns.nl/mvoberekeningen. (Dutch only)Changes: Improvements have been made to the method for measuring delays; this could only be done retrospectively for 2015. The old method was used for 2014. For safety with respect to the car, we made use of a more up-to-date external source and incorporated this in retrospective calculations for 2015 and 2014.A corrective factor is applied for inflation for each year.In many of the themes, NS works with partners to improve the results and the social impact. Together with ProRail, we are for example improving rail safety, punctuality and journey times. Despite the fact that a share of the impact in many of the themes could be assigned to our partners in the sector, we are not yet going so in the calculations. We are looking at methods for including such a split in subsequent publications. The positive and negative impacts are being presented separately for each topic, given that it is not possible to balance them off against each other (because the positive impact is often expressed as the difference with respect to transport by car).