Data sources Approved approaches require the use of data and assumptions to estimate emissions and removals from the baseline scenario and project interventions. Potential data sources include: Surveys or research conducted within the project area or other representative areas Analysis of maps and remote sending data Published and unpublished papers and reports from the region Default values from national or global studies. Data sources used must contribute to a credible and conservative estimation of climate benefits, and projects are encouraged to make use of available sources of information where possible, to reduce the cost of data collection, and increase the speed of approval. Where appropriate data is not available, or the cost of data collection is prohibitive, conservative assumptions can be used. All assumptions and sources of data must be identified within the PDD. A justification of why they are appropriate should be provided: For the baselines scenario (PDD Section G4) For the project intervention (PDD Section G5) For leakage (PDD Section G6) For projects who conducted their own surveys, research or mapping, full details of data collection and analysis methodologies and results must be included in the PDD Annex.