Question

我正在尝试使用模拟，从总体中抽取1到1000个样本，平均值为50，标准差为10。计算每个样本的平均值，并绘制一个图，显示该平均值随您的变化而变化增加样本量。根据该图，均值是总体均值的有偏估计或无偏估计？

以下是我所做的：

sd_uncorrected<-function(x){ return(sqrt(sum((x-mean(x))^2)/length(x)))
}

population <- rnorm(n = 1000, mean = 50, sd = 10) 
population_mean <- mean(population) 
population_std <- sd_uncorrected(population)

paste('population mean=',population_mean)
paste('population std = ', population_std)

sample_size <- 1000 # how many elements we want to sample
sample_n <- sample(population, size = sample_size, replace = FALSE) 
sample_n

mean(sample_n)
sd_uncorrected(sample_n)

n_experiments <- 1000 # we will sample 1000 times
sample_size <- 10 # how many elements we want to sample?
sample_means <- c()

library(ggplot2)
sample_means_df <- data.frame(means=sample_means)
ggplot(sample_means_df, aes(x=means)) + geom_histogram() +
geom_vline(xintercept = population_mean, color='red') + # population mean
geom_vline(xintercept = mean(sample_means_df$means), color='black')

我收到以下错误消息，但我不知道该怎么办。有人可以帮我吗？

Error in FUN(X[[i]], ...) : object 'means' not found
In addition: Warning message:
In mean.default(sample_means_df$means) :
argument is not numeric or logical: returning NA

Answer 1

也许应该写

sample_means = replicate(sample_size, 
                         mean(sample(population, size = sample_size, replace = FALSE) ))

一行之后

sample_means <- c()

如评论中所述，您声明了一个不包含sample_means内容的向量

我如何绘制均值？

1 个答案: