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這可能是個愚蠢的問題。但我想澄清。 如果X遵循對數正態,那麼log(X)遵循正態分佈 我想知道dlnorm不等於dnorm,爲什麼?但是plnorm等於pnorm!dlnorm是否等於dnorm?
> u=5
> s=0.5
> u
[1] 5
> s
[1] 0.5
> T=84.5
> dist_log=plnorm(T, meanlog=u, sdlog=s)
> dist_log
[1] 0.1299776194
> dist_norm=pnorm(log(T), mean=u, sd=s)
> dist_norm
[1] 0.1299776194
> den_log=dlnorm(T, meanlog=u, sdlog=s)
> den_log
[1] 0.005006388135
> den_norm=dnorm(log(T), mean=u, sd=s)
> den_norm
[1] 0.4230397974