1d:T660,# Constructs the correction-factor used when back-transforming log-transformed values. Constructs the correction-factor used when back-transforming log-transformed values according to Sprugel (1983). Sprugel's main formula -- exp((syx^2)/2) -- is used when syx is estimated for natural log transformed data. A correction for any base is obtained by multiplying the syx term by log_e(base) to give exp(((log_e(base)*syx)^2)/2). This more general formula is implemented here (if, of course, the base is exp(1) then the general formula reduces to the original specific formula). ```r logbtcf(obj, base = exp(1)) ``` ## Arguments - `obj`: An object from `lm`. - `base`: A single numeric that indicates the base of the logarithm used. ## Returns A numeric value that is the correction factor according to Sprugel (1983). ## Examples ```r # toy data df <- data.frame(y=rlnorm(10),x=rlnorm(10)) df$logey <- log(df$y) df$log10y <- log10(df$y) df$logex <- log(df$x) df$log10x <- log10(df$x) # model and predictions on loge scale lme <- lm(logey~logex,data=df) ( ploge <- predict(lme,data.frame(logex=log(10))) ) ( pe <- exp(ploge) ) ( cfe <- logbtcf(lme) ) ( cpe <- cfe*pe ) # model and predictions on log10 scale lm10 <- lm(log10y~log10x,data=df) plog10 <- predict(lm10,data.frame(log10x=log10(10))) p10 <- 10^(plog10) ( cf10 <- logbtcf(lm10,10) ) ( cp10 <- cf10*p10 ) # cfe and cf10, cpe and cp10 should be equal all.equal(cfe,cf10) all.equal(cpe,cp10) ``` ## References Sprugel, D.G. 1983. Correcting for bias in log-transformed allometric equations. Ecology 64:209-210. ## Author(s) Derek H. Ogle, DerekOgle51@gmail.com1e:T49a,M7.49933 0.25C3.49635 0.25 0.25 3.49593 0.25 7.50024C0.25 10.703 2.32715 13.4206 5.2081 14.3797C5.57084 14.446 5.70302 14.2222 5.70302 14.0299C5.70302 13.8576 5.69679 13.4019 5.69323 12.797C3.67661 13.235 3.25112 11.825 3.25112 11.825C2.92132 10.9874 2.44599 10.7644 2.44599 10.7644C1.78773 10.3149 2.49584 10.3238 2.49584 10.3238C3.22353 10.375 3.60629 11.0711 3.60629 11.0711C4.25298 12.1788 5.3033

logbtcf function