Project
Implementing probabilistic sampling in Demersal Market Sampling Scheme and evaluating the estimating process
The new Regional Database and Estimation System (RDBES), currently developed by ICES is aiming to replace both RDB and Intercatch in 2022. The key principles of RDBES include 1) documentation of sampling design and process, 2) conducting probabilistic selection in sampling, and 3) providing better statistical estimation of catches. To meet the goal of RDBES, In a 2020-2021 KBWOT project, we have converted our hierarchical sampling design into RDBES structure, produced quality control and report of sampling process (using Rmarkdown), optimized sampling efforts for dab and flounder to provide better estimate. We also aimed to carry out probabilistic selection in all levels of sampling design. A tool was developed to help observer randomly select market-day and record non-response. However, conducting probabilistic selection of vessels at the market is difficult, since it was constrained by practical issues such as lack of information onsite, processing time as well as observers will. Instead, we developed a simple Rshiny tool in this project to mainly focusing on recording non-response and getting observers feedback. We have made a concept design for probabilistic sampling tool, the next step is to implement it if the observer feels comfortable using it. Therefore, for the follow up work to meet the goal of conducting probabilistic selection, we aim to develop such Rshiny tool to help observer in selecting trips at the market. Different estimation methods can be applied to the same sampling design. Based on the characteristic of the catch data, some estimates can be slightly biased but more precise than others (i.e. smaller variance). It is also the goal of RDBES to find the best estimation method for each national sampling data.
De herziene versie van de Data Collectie Verordening (DCF) in combinatie met de graduele invoering van de aanlandplicht hebben als gevolg dat de bestaande WOT bemonsteringsprogrammas Marktbemonstering zeevisserij en Monitoring bijvangsten (ookwel het markt en discards project genoemd) aangepast moeten gaan worden. Het doel van dit project is om een statistisch betrouwbaar, praktisch en financieel haalbaar bemonsteringsprogramma te ontwerpen voor het monitoren van de biologische gegevens van de Nederlandse commerciële vangsten. Met als doel om bruikbare kwantitatieve waardevolle gegevens te verzamelen voor de eindgebruiker (bijv. ICES, STECF, Ministerie van EZ).