[我正在尝试使用R模仿图形板ELISA分析,但是我在获取P值和R ^ 2值方面有些困难。
[使用名为“ minpack.lm”的程序包为我提供了大多数信息,但是我不确定如何从此处获取R ^ 2和P值。
ODCalc1 <- c(.007, .072, .328, .988, 1.534, 1.983)
ODCalc2 <- c(.006, .074, .361, .858, 1.612, 1.993)
ODCalc <- (ODCalc1 + ODCalc2)/2
concentration <- log10(c(1, 36, 180, 540, 1080, 1800))
ocon <- data.frame(10^(concentration), "rep", ODCalc, stringsAsFactors = F)
ocon$X.rep. <- as.numeric(ocon$X.rep.)
ocon$X.rep. <- 1
names(ocon) <- c("conc", "rep", "od")
# Plot the O'Connell data
par(mfrow = c(1, 2), cex.main = 1, mar = c(4, 4, 1, 2), oma = c(0.5, 0.5, 2.5, 0))
plot(ocon$conc, ocon$od, pch = 21, bg = "grey", ylab = "Response (od)",
xlab = "Concentration")
grid()
# Plot on the log(x) scale
plot(log(ocon$conc), ocon$od, pch = 21, bg = "grey", ylab = "Response (od)",
xlab = "log(concentration)")
grid()
title("O'Connell's ELISA: concentration on absolute (left) and log (right) scales",
outer = T)
par(mfrow = c(1, 1))
# ------------ Function: 4PL curve function ---------------------------------
M.4pl <- function(x, small.x.asymp, inf.x.asymp, inflec, hill){
f <- small.x.asymp + ((inf.x.asymp - small.x.asymp)/
(1 + (x / inflec)^hill))
return(f)
}
# ------------- end ---------------------------------------------------------
start.ocon <- c(small.x.asymp = 0.1, inf.x.asymp = 1, inflec = 3000, hill = -1)
library(minpack.lm)
uw.4pl <- nlsLM(od ~ M.4pl(conc, small.x.asymp, inf.x.asymp, inflec, hill),
data = ocon,
start = start.ocon)
data.4pl <- summary(uw.4pl)
bottom.4pl <- data.4pl$parameters[1,1]
top.4pl <- data.4pl$parameters[2,1]
IC50.4pl <- data.4pl$parameters[3,1]
HillSlope.4pl <- abs(data.4pl$parameters[4,1])
RSS.p <- sum(residuals(uw.4pl)^2)
TSS <- sum((ocon$od - mean(ocon$od))^2)
r.squared <- 1-(RSS.p/TSS) # is this the proper way to get an r^2 value? It does not match what graphpad has which is an issue.
# I have also read this should work, but since the model is a linear model instead of a Sigmoidal, 4PL, X is log (concentration) model
model <- lm(concentration ~ poly(ODCalc, degree = 4, raw=T))
summary(model) # R^2 is not the correct value I am looking for.
# Not sure if sample data is needed but these were the values we were using to produce the values below
sample.od.values1 <- c(0.275, 1.18, 0.085, 0.054, 0.119)
sample.od.values2 <- c(0.263, 1.149, 0.068, 0.062, 0.109)
sample.od.values <- (sample.od.values1+sample.od.values2)/2
证明方法相同的值:
bottom.4pl = 0.01657
top.4pl = 3.002
HillSlope = 1.222
R ^ 2 = 0.9978
R ^ 2(adjusted)= 0.9969
P值= 0.5106
预先感谢您提供任何有用的提示!
由于R ^ 2测量线性关联,所以通常将其用于线性回归,但是忽略了这似乎给出了您想要的数字或至少接近那些数字。对于p值,我假设您正在寻找第一个系数为零的假设的p值。
RSS <- deviance(uw.4pl); RSS
## [1] 0.001514624
coef(uw.4pl) # coefficients/parameters
## small.x.asymp inf.x.asymp inflec hill
## 0.01654996 3.00261439 1033.53324214 -1.22171740
R2 <- cor(ocon$od, fitted(uw.4pl))^2; R2
## [1] 0.9995529
n <- nobs(ocon)
p <- length(coef(fm1))
adjR2 <- 1 - (1-R2) * (n - 1) / (n - p - 1); adjR2
## [1] 0.9977645
pvalue <- coef(summary(uw.4pl))[1, 4]; pvalue
## [1] 0.5486584