How strong should my anchor be for estimating group and individual level meaningful change? A simulation study assessing anchor correlation strength and the impact of sample size, distribution of change scores and methodology on establishing a true meaningful change threshold - Griffiths, Pip; Sims, Joel; Williams, Abi; Williamson, Nicola; Cella, David; Brohan, Elaine; Cocks, Kim (Quality of Life Research, 2023)