# Consider the scales of your variables
# Note: when 2 variables have very different ranges of scale the criteria mixed models use to come up
# with parameter estimates are likely to return 'convergance errors'
# Z correcting adjusts for this scaling problem:
# What is a z correction?: (z = (x - mean(x))/sd(x))
# Z-correct Length
data$Z_Length<-(data$Fish_Length-mean(data$Fish_Length))/sd(data$Fish_Length)
# Z-correct Trophic Position
data$Z_TP<-(data$Trophic_Pos-mean(data$Trophic_Pos))/sd(data$Trophic_Pos)