Question

In R, how to use pt( ) to find the one-sided left-tail p-value for t=-1.98 with df=8? And what is the one-sided right-tail p-value for t=1.98 with df=8? And what is the two-sided p-value for t=1.98 with df=8?

Print the code please, thank you!

Answer #1

To get one sided left tail p-value for t= -1.98 with df 8, the R-code is:

pt(-1.98,8,lower.tail = TRUE)

[1] 0.04152436

(When lower.tail= TRUE you get the probability to the left of the distribution)

To get one sided right tail p-value for t= 1.98 with df 8, the R-code is:

pt(1.98,8,lower.tail = FALSE)

[1] 0.04152436

(When lower.tail= FALSE you get the probability to the right of the distribution)

To get two sided right tail p-value for t= 1.98 with df 8, the R-code is:

2*pt(1.98,8,lower.tail = FALSE)

[1] 0.08304872

Find the P-value for the indicated hypothesis test. [8]15)a)
Assume a left tail test under a normal distribution with an outcome
whose z_score is-1.18b) Assume a samplle of size 38, a right-tailed
test under a t-distribution whose t_value is1.687c) Assume a
two-tailed test, normal distribution and a sample whose z_score is
1.54.d) Assume a left_tailed test, chi-square distribution and a
sample of size 12 whosechi_square statistc is 3.053

State and support whether the p-value (from the test statistic)
will be applied in a left-tail, right-tail, or two-tail test.

(a) Find the t-value such that the area in the right tail is
0.15 with 18 degrees of freedom. nothing (Round to three decimal
places as needed.)
(b) Find the t-value such that the area in the right tail is
0.01 with 9 degrees of freedom. nothing (Round to three decimal
places as needed.)
(c) Find the t-value such that the area left of the t-value is
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t=
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t=
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1. In R, inverse probability distribution functions start with q
(no reason why really; it’s just a convention). To calculate the
critical value for a two-tailed t-test with n
− k = 100 and α = 0.05, use the inverse
t distribution command. For the inverse t function, type
qt(1-0.05/2, 100). To find the one-tailed critical value for a
t distribution for α = 0.01 and 100 degrees of
freedom, type qt(1-0.01, 100).
2. To find the critical value from...

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Will you use a left tail, right tail or 2 tailed test?
Identify the sampling distribution to be used: standard normal,
Student’s t or chi squared.
Find the value of the test statistic.
Find the P-Valu
Based on your answers, shall we reject or accept the null
hypothesis?
Write the conclusion in the context of the problem.
Flying time on an old route between 2 cities has a mean
value of =5.25 hours with...

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(a) Find the t-value such that the area in the right tail is
0.25 with 9 degrees of freedom. nothing (Round to three decimal
places as needed.)
(b) Find the t-value such that the area in the right tail is
0.05 with 16 degrees of freedom. nothing (Round to three decimal
places as needed.)
(c) Find the t-value such that the area left of the t-value
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(a) Find the t-value such that the area in the right tail is
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as needed.)
(b) Find the t-value such that the area in the right tail is
0.01 with 23 degrees of freedom. (Round to three decimal places
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(c) Find the t-value such that the area left of the t-value
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B.) Find the t-value such that the area in the right tail is
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C.) Find the t-value such that the area left of the t-value is
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The value of the test statistic for a one-sample t-test for 21
observations is 1.86.
Question 1: The correct R instruction for finding the P-value
for a right-tailed test is: A. 1-pt(1.86, 20) B. 1-pt (1.86,21) C.
pt(1.86,21) D. pt(1.86, 20)
Question 2: The correct R instruction for finding the P-value
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