how to check a propriety using r studio
$begingroup$
I have to check that this propriety
$Z sim N(0,1)$ and $Usim chi ^{2}(10)$ then $ Z/sqrt{U/10} sim T(10)$
is true using r studio if anyone can help , much appreciate
probability statistics hypothesis-testing
$endgroup$
add a comment |
$begingroup$
I have to check that this propriety
$Z sim N(0,1)$ and $Usim chi ^{2}(10)$ then $ Z/sqrt{U/10} sim T(10)$
is true using r studio if anyone can help , much appreciate
probability statistics hypothesis-testing
$endgroup$
3
$begingroup$
What do you mean by "verify using R"? A programming language cannot rigorously verify this although it may produce evidence suggesting it is true. If you read the definition of a $t$-distribution, then your question follows almost immediately.
$endgroup$
– angryavian
11 hours ago
$begingroup$
@angryavian : Maybe not in r studio (although I don't know all the capabilities of R), but there's a thing called computer-assisted proofs.
$endgroup$
– Raskolnikov
8 hours ago
$begingroup$
@angryavian you can use R to sample from the distributions in question and use that to do some hypothesis testing.
$endgroup$
– JJJ
6 hours ago
add a comment |
$begingroup$
I have to check that this propriety
$Z sim N(0,1)$ and $Usim chi ^{2}(10)$ then $ Z/sqrt{U/10} sim T(10)$
is true using r studio if anyone can help , much appreciate
probability statistics hypothesis-testing
$endgroup$
I have to check that this propriety
$Z sim N(0,1)$ and $Usim chi ^{2}(10)$ then $ Z/sqrt{U/10} sim T(10)$
is true using r studio if anyone can help , much appreciate
probability statistics hypothesis-testing
probability statistics hypothesis-testing
asked 11 hours ago
JoshuaKJoshuaK
305
305
3
$begingroup$
What do you mean by "verify using R"? A programming language cannot rigorously verify this although it may produce evidence suggesting it is true. If you read the definition of a $t$-distribution, then your question follows almost immediately.
$endgroup$
– angryavian
11 hours ago
$begingroup$
@angryavian : Maybe not in r studio (although I don't know all the capabilities of R), but there's a thing called computer-assisted proofs.
$endgroup$
– Raskolnikov
8 hours ago
$begingroup$
@angryavian you can use R to sample from the distributions in question and use that to do some hypothesis testing.
$endgroup$
– JJJ
6 hours ago
add a comment |
3
$begingroup$
What do you mean by "verify using R"? A programming language cannot rigorously verify this although it may produce evidence suggesting it is true. If you read the definition of a $t$-distribution, then your question follows almost immediately.
$endgroup$
– angryavian
11 hours ago
$begingroup$
@angryavian : Maybe not in r studio (although I don't know all the capabilities of R), but there's a thing called computer-assisted proofs.
$endgroup$
– Raskolnikov
8 hours ago
$begingroup$
@angryavian you can use R to sample from the distributions in question and use that to do some hypothesis testing.
$endgroup$
– JJJ
6 hours ago
3
3
$begingroup$
What do you mean by "verify using R"? A programming language cannot rigorously verify this although it may produce evidence suggesting it is true. If you read the definition of a $t$-distribution, then your question follows almost immediately.
$endgroup$
– angryavian
11 hours ago
$begingroup$
What do you mean by "verify using R"? A programming language cannot rigorously verify this although it may produce evidence suggesting it is true. If you read the definition of a $t$-distribution, then your question follows almost immediately.
$endgroup$
– angryavian
11 hours ago
$begingroup$
@angryavian : Maybe not in r studio (although I don't know all the capabilities of R), but there's a thing called computer-assisted proofs.
$endgroup$
– Raskolnikov
8 hours ago
$begingroup$
@angryavian : Maybe not in r studio (although I don't know all the capabilities of R), but there's a thing called computer-assisted proofs.
$endgroup$
– Raskolnikov
8 hours ago
$begingroup$
@angryavian you can use R to sample from the distributions in question and use that to do some hypothesis testing.
$endgroup$
– JJJ
6 hours ago
$begingroup$
@angryavian you can use R to sample from the distributions in question and use that to do some hypothesis testing.
$endgroup$
– JJJ
6 hours ago
add a comment |
3 Answers
3
active
oldest
votes
$begingroup$
One approach could be simulation of thousands of values:
- Simulate $Z$ using
rnorm
- Simulate $U$ using
rchisq
- Do the division $Y = Z / sqrt{U / 10}$
- Simulate the same number of $T$ from the hypothesised $t$-distribution using
rt
- Sort $Y$ and $T$ and plot them against each other - you want to see a diagonal straight line essentially $y=x$ with a little noise; this is visual demonstration though not a proof that the distributions are the same
You can do similar things with the qqplot
function if you know what you are doing
$endgroup$
add a comment |
$begingroup$
I agree with @angryavian that you can't do a 'proof' in R.
Also, it is crucial to state that random variables $Z$
and $U$ are independent. Then $Y = frac{Z}{U/sqrt{10}} sim mathsf{T}(10)$ by definition.
Here is R code to simulate a million values of $T$ [as in the Answer of @Henry (+1)], then to compare their histogram with the density of $mathsf{T}(10).$ This
is a graphical demonstration that $T$ has (at least very nearly) the claimed t distribution.
set.seed(405) # for reproducibility
z = rnorm(10^6); u = rchisq(10^6, 10)
y = z/sqrt(u/10)
hist(y, prob=T, br=50, col="skyblue2")
curve(dt(x, 10), add=T, lwd=2)
Furthermore, you could check that the quantiles of $Y$ very nearly match the theoretical quantiles of $mathsf{T}(10).$
summary(y)
Min. 1st Qu. Median Mean 3rd Qu. Max.
-10.641101 -0.699409 0.000059 0.000221 0.701253 9.802922
qt(c(.25,.5,.75), 10)
[1] -0.6998121 0.0000000 0.6998121
The summary above also shows that $bar Y approx 0.$ And the sample variance of the simulated values of $Y$ is very nearly the variance $nu/(nu - 2) = 10/8 = 1.25$ of Student's t distribution with $nu = 10$ degrees of freedom.
[In effect, two of the moments suggested by #GeorgeDewhirts (+1).]
var(y); 10/8
[1] 1.250115
[1] 1.25
Also, you could do a Kolmogorov-Smirnov goodness-of-fit test on the first 5000 values of $Y$ and check that the P-value exceeds 5%. (The K-S test in R is limited to 5000 observations.) Roughly speaking, this is a formal, quantitative way to do @Henry's comparison of sorted observations.
ks.test(y[1:5000], pt, 10)
One-sample Kolmogorov-Smirnov test
data: y[1:5000]
D = 0.013661, p-value = 0.3083
alternative hypothesis: two-sided
$endgroup$
add a comment |
$begingroup$
You could compare the moments of your distribution with the theoretical moments of $T(10)$
$endgroup$
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
One approach could be simulation of thousands of values:
- Simulate $Z$ using
rnorm
- Simulate $U$ using
rchisq
- Do the division $Y = Z / sqrt{U / 10}$
- Simulate the same number of $T$ from the hypothesised $t$-distribution using
rt
- Sort $Y$ and $T$ and plot them against each other - you want to see a diagonal straight line essentially $y=x$ with a little noise; this is visual demonstration though not a proof that the distributions are the same
You can do similar things with the qqplot
function if you know what you are doing
$endgroup$
add a comment |
$begingroup$
One approach could be simulation of thousands of values:
- Simulate $Z$ using
rnorm
- Simulate $U$ using
rchisq
- Do the division $Y = Z / sqrt{U / 10}$
- Simulate the same number of $T$ from the hypothesised $t$-distribution using
rt
- Sort $Y$ and $T$ and plot them against each other - you want to see a diagonal straight line essentially $y=x$ with a little noise; this is visual demonstration though not a proof that the distributions are the same
You can do similar things with the qqplot
function if you know what you are doing
$endgroup$
add a comment |
$begingroup$
One approach could be simulation of thousands of values:
- Simulate $Z$ using
rnorm
- Simulate $U$ using
rchisq
- Do the division $Y = Z / sqrt{U / 10}$
- Simulate the same number of $T$ from the hypothesised $t$-distribution using
rt
- Sort $Y$ and $T$ and plot them against each other - you want to see a diagonal straight line essentially $y=x$ with a little noise; this is visual demonstration though not a proof that the distributions are the same
You can do similar things with the qqplot
function if you know what you are doing
$endgroup$
One approach could be simulation of thousands of values:
- Simulate $Z$ using
rnorm
- Simulate $U$ using
rchisq
- Do the division $Y = Z / sqrt{U / 10}$
- Simulate the same number of $T$ from the hypothesised $t$-distribution using
rt
- Sort $Y$ and $T$ and plot them against each other - you want to see a diagonal straight line essentially $y=x$ with a little noise; this is visual demonstration though not a proof that the distributions are the same
You can do similar things with the qqplot
function if you know what you are doing
answered 10 hours ago
HenryHenry
101k482170
101k482170
add a comment |
add a comment |
$begingroup$
I agree with @angryavian that you can't do a 'proof' in R.
Also, it is crucial to state that random variables $Z$
and $U$ are independent. Then $Y = frac{Z}{U/sqrt{10}} sim mathsf{T}(10)$ by definition.
Here is R code to simulate a million values of $T$ [as in the Answer of @Henry (+1)], then to compare their histogram with the density of $mathsf{T}(10).$ This
is a graphical demonstration that $T$ has (at least very nearly) the claimed t distribution.
set.seed(405) # for reproducibility
z = rnorm(10^6); u = rchisq(10^6, 10)
y = z/sqrt(u/10)
hist(y, prob=T, br=50, col="skyblue2")
curve(dt(x, 10), add=T, lwd=2)
Furthermore, you could check that the quantiles of $Y$ very nearly match the theoretical quantiles of $mathsf{T}(10).$
summary(y)
Min. 1st Qu. Median Mean 3rd Qu. Max.
-10.641101 -0.699409 0.000059 0.000221 0.701253 9.802922
qt(c(.25,.5,.75), 10)
[1] -0.6998121 0.0000000 0.6998121
The summary above also shows that $bar Y approx 0.$ And the sample variance of the simulated values of $Y$ is very nearly the variance $nu/(nu - 2) = 10/8 = 1.25$ of Student's t distribution with $nu = 10$ degrees of freedom.
[In effect, two of the moments suggested by #GeorgeDewhirts (+1).]
var(y); 10/8
[1] 1.250115
[1] 1.25
Also, you could do a Kolmogorov-Smirnov goodness-of-fit test on the first 5000 values of $Y$ and check that the P-value exceeds 5%. (The K-S test in R is limited to 5000 observations.) Roughly speaking, this is a formal, quantitative way to do @Henry's comparison of sorted observations.
ks.test(y[1:5000], pt, 10)
One-sample Kolmogorov-Smirnov test
data: y[1:5000]
D = 0.013661, p-value = 0.3083
alternative hypothesis: two-sided
$endgroup$
add a comment |
$begingroup$
I agree with @angryavian that you can't do a 'proof' in R.
Also, it is crucial to state that random variables $Z$
and $U$ are independent. Then $Y = frac{Z}{U/sqrt{10}} sim mathsf{T}(10)$ by definition.
Here is R code to simulate a million values of $T$ [as in the Answer of @Henry (+1)], then to compare their histogram with the density of $mathsf{T}(10).$ This
is a graphical demonstration that $T$ has (at least very nearly) the claimed t distribution.
set.seed(405) # for reproducibility
z = rnorm(10^6); u = rchisq(10^6, 10)
y = z/sqrt(u/10)
hist(y, prob=T, br=50, col="skyblue2")
curve(dt(x, 10), add=T, lwd=2)
Furthermore, you could check that the quantiles of $Y$ very nearly match the theoretical quantiles of $mathsf{T}(10).$
summary(y)
Min. 1st Qu. Median Mean 3rd Qu. Max.
-10.641101 -0.699409 0.000059 0.000221 0.701253 9.802922
qt(c(.25,.5,.75), 10)
[1] -0.6998121 0.0000000 0.6998121
The summary above also shows that $bar Y approx 0.$ And the sample variance of the simulated values of $Y$ is very nearly the variance $nu/(nu - 2) = 10/8 = 1.25$ of Student's t distribution with $nu = 10$ degrees of freedom.
[In effect, two of the moments suggested by #GeorgeDewhirts (+1).]
var(y); 10/8
[1] 1.250115
[1] 1.25
Also, you could do a Kolmogorov-Smirnov goodness-of-fit test on the first 5000 values of $Y$ and check that the P-value exceeds 5%. (The K-S test in R is limited to 5000 observations.) Roughly speaking, this is a formal, quantitative way to do @Henry's comparison of sorted observations.
ks.test(y[1:5000], pt, 10)
One-sample Kolmogorov-Smirnov test
data: y[1:5000]
D = 0.013661, p-value = 0.3083
alternative hypothesis: two-sided
$endgroup$
add a comment |
$begingroup$
I agree with @angryavian that you can't do a 'proof' in R.
Also, it is crucial to state that random variables $Z$
and $U$ are independent. Then $Y = frac{Z}{U/sqrt{10}} sim mathsf{T}(10)$ by definition.
Here is R code to simulate a million values of $T$ [as in the Answer of @Henry (+1)], then to compare their histogram with the density of $mathsf{T}(10).$ This
is a graphical demonstration that $T$ has (at least very nearly) the claimed t distribution.
set.seed(405) # for reproducibility
z = rnorm(10^6); u = rchisq(10^6, 10)
y = z/sqrt(u/10)
hist(y, prob=T, br=50, col="skyblue2")
curve(dt(x, 10), add=T, lwd=2)
Furthermore, you could check that the quantiles of $Y$ very nearly match the theoretical quantiles of $mathsf{T}(10).$
summary(y)
Min. 1st Qu. Median Mean 3rd Qu. Max.
-10.641101 -0.699409 0.000059 0.000221 0.701253 9.802922
qt(c(.25,.5,.75), 10)
[1] -0.6998121 0.0000000 0.6998121
The summary above also shows that $bar Y approx 0.$ And the sample variance of the simulated values of $Y$ is very nearly the variance $nu/(nu - 2) = 10/8 = 1.25$ of Student's t distribution with $nu = 10$ degrees of freedom.
[In effect, two of the moments suggested by #GeorgeDewhirts (+1).]
var(y); 10/8
[1] 1.250115
[1] 1.25
Also, you could do a Kolmogorov-Smirnov goodness-of-fit test on the first 5000 values of $Y$ and check that the P-value exceeds 5%. (The K-S test in R is limited to 5000 observations.) Roughly speaking, this is a formal, quantitative way to do @Henry's comparison of sorted observations.
ks.test(y[1:5000], pt, 10)
One-sample Kolmogorov-Smirnov test
data: y[1:5000]
D = 0.013661, p-value = 0.3083
alternative hypothesis: two-sided
$endgroup$
I agree with @angryavian that you can't do a 'proof' in R.
Also, it is crucial to state that random variables $Z$
and $U$ are independent. Then $Y = frac{Z}{U/sqrt{10}} sim mathsf{T}(10)$ by definition.
Here is R code to simulate a million values of $T$ [as in the Answer of @Henry (+1)], then to compare their histogram with the density of $mathsf{T}(10).$ This
is a graphical demonstration that $T$ has (at least very nearly) the claimed t distribution.
set.seed(405) # for reproducibility
z = rnorm(10^6); u = rchisq(10^6, 10)
y = z/sqrt(u/10)
hist(y, prob=T, br=50, col="skyblue2")
curve(dt(x, 10), add=T, lwd=2)
Furthermore, you could check that the quantiles of $Y$ very nearly match the theoretical quantiles of $mathsf{T}(10).$
summary(y)
Min. 1st Qu. Median Mean 3rd Qu. Max.
-10.641101 -0.699409 0.000059 0.000221 0.701253 9.802922
qt(c(.25,.5,.75), 10)
[1] -0.6998121 0.0000000 0.6998121
The summary above also shows that $bar Y approx 0.$ And the sample variance of the simulated values of $Y$ is very nearly the variance $nu/(nu - 2) = 10/8 = 1.25$ of Student's t distribution with $nu = 10$ degrees of freedom.
[In effect, two of the moments suggested by #GeorgeDewhirts (+1).]
var(y); 10/8
[1] 1.250115
[1] 1.25
Also, you could do a Kolmogorov-Smirnov goodness-of-fit test on the first 5000 values of $Y$ and check that the P-value exceeds 5%. (The K-S test in R is limited to 5000 observations.) Roughly speaking, this is a formal, quantitative way to do @Henry's comparison of sorted observations.
ks.test(y[1:5000], pt, 10)
One-sample Kolmogorov-Smirnov test
data: y[1:5000]
D = 0.013661, p-value = 0.3083
alternative hypothesis: two-sided
edited 8 hours ago
answered 9 hours ago
BruceETBruceET
36.2k71540
36.2k71540
add a comment |
add a comment |
$begingroup$
You could compare the moments of your distribution with the theoretical moments of $T(10)$
$endgroup$
add a comment |
$begingroup$
You could compare the moments of your distribution with the theoretical moments of $T(10)$
$endgroup$
add a comment |
$begingroup$
You could compare the moments of your distribution with the theoretical moments of $T(10)$
$endgroup$
You could compare the moments of your distribution with the theoretical moments of $T(10)$
answered 10 hours ago
George DewhirstGeorge Dewhirst
7164
7164
add a comment |
add a comment |
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3
$begingroup$
What do you mean by "verify using R"? A programming language cannot rigorously verify this although it may produce evidence suggesting it is true. If you read the definition of a $t$-distribution, then your question follows almost immediately.
$endgroup$
– angryavian
11 hours ago
$begingroup$
@angryavian : Maybe not in r studio (although I don't know all the capabilities of R), but there's a thing called computer-assisted proofs.
$endgroup$
– Raskolnikov
8 hours ago
$begingroup$
@angryavian you can use R to sample from the distributions in question and use that to do some hypothesis testing.
$endgroup$
– JJJ
6 hours ago