B***a
发帖数: 21 | 1 我想知道“每周工作小时数”是否是正太分布，做了qnorm 和pnorm图，请问如何读这
个结果？ qnorm的左尾有偏离，怎么办？ 我的样本大于20000，可否根据CLT假定其会
服从正太？run过 sktest， 通不过。 |
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b******v
发帖数: 1493 | 2 由题目条件可以知道mu/sigma = qnorm(0.16)
而四个quarter之和是一个N(4mu, 2sigma)的正态分布
根据积分里换元法，它为负的概率是pnorm(2*qnorm(0.16)) = 0.023355
以上qnorm和pnorm都是统计软件R里的函数 |
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r***a
发帖数: 58 | 3 First of all 81.94% is not low for a R square. Indeed, it is a decent one.
You should also look at the p-values of the coefficients, see if they
all are significant. If not, you can consider get rid of those non significant
ones one by one and fit the model. For sure, the less coefficent you have
in your model, the smaller R square you will get. Keep in mind that R square
is not the only criteria for model fitting.
You can also try qnorm plot to see if the residuas are normally distributed.
You |
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f****s
发帖数: 1 | 4 把R的the standalone Rmath library单独编译出来，里面有qnorm等函数 |
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n********g
发帖数: 218 | 5 我不太懂R，所以问个白痴的问题，请大家帮帮忙
我用R在RUN一个LOOP循环5次，下面是我的部分CODES：
for i in seq(5)
{ n=100
x=runif(n,-1,1)
y=1+x+rnorm(n,0,1)
# 通过一个fit 得到 S(x)
S(x)=fit$y
Z=qnorm(S(x))
fit2=lm(d~z)
等等
}
这个循环中S(x)可能会产生数据0而导致Z会有Inf，这在fit2中就出现了错误。所以
请交大家怎么写个条件句，如果出现S(x)有0或者Z有Inf的话就重新run一次，直到最后
5次循环后的结果都没有上面的问题。
先谢谢啦！！！ |
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j*****7
发帖数: 7 | 6 j<-1
while(j<=5)
{ n=100
x=runif(n,-1,1)
y=1+x+rnorm(n,0,1)
# 通过一个fit 得到 S(x)
if(出现S(x)有0或者Z有Inf的话) next;
else{ j<-j+1
S(x)=fit$y
Z=qnorm(S(x))
fit2=lm(d~z)
等等
}
} |
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w*******9
发帖数: 1433 | 7 Clt only concerns the asymptotic distribution of sample mean. It probably
does not apply to this case. If I am wrong, please correct me: there might
be one or several zeros in your data. Delete these and try again. |
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