Foot-Length: It has been claimed that, on average, right-handed people have a le
ID: 3216711 • Letter: F
Question
Foot-Length: It has been claimed that, on average, right-handed people have a left foot that is larger than the right foot. Here we test this claim on a sample of 10 right-handed adults. The table below gives the left and right foot measurements in millimeters (mm). Test the claim at the 0.01 significance level. You may assume the sample of differences comes from a normally distributed population.
If you are using software, you should be able copy and paste the data directly into your software program.
(a) The claim is that the mean difference is positive (d > 0). What type of test is this?
This is a right-tailed test.
This is a left-tailed test.
This is a two-tailed test.
(b) What is the test statistic? Round your answer to 2 decimal places.
td =
To account for hand calculations -vs- software, your answer must be within 0.01 of the true answer.
(c) Use software to get the P-value of the test statistic. Round to 4 decimal places.
P-value =
(d) What is the conclusion regarding the null hypothesis?
reject H0
fail to reject H0
(e) Choose the appropriate concluding statement.
The data supports the claim that, on average, right-handed people have a left foot that is larger than the right foot.
There is not enough data to support the claim that, on average, right-handed people have a left foot that is larger than the right foot.
We reject the claim that, on average, right-handed people have a left foot that is larger than the right foot.
We have proven that, on average, right-handed people have a left foot that is larger than the right foot.
Person Left Foot (x) Right Foot (y) difference (d = x y) 1 272 272 0 2 269 267 2 3 259 261 -2 4 255 254 1 5 261 258 3 6 273 273 0 7 274 270 4 8 258 256 2 9 273 272 1 10 255 253 2 Mean 264.90 263.60 1.30 s 7.99 8.04 1.70Explanation / Answer
Given that,
population mean(u)=259
sample mean, x =255
standard deviation, s =261
number (n)=273
null, H0: Ud < 0
alternate, H1: Ud > 0
level of significance, = 0.01
from standard normal table,right tailed t /2 =2.821
since our test is right-tailed
reject Ho, if to > 2.821
we use Test Statistic
to= d/ (S/n)
Where
Value of S^2 = [ di^2 – ( di )^2 / n ] / ( n-1 ) )
d = ( Xi-Yi)/n) = 1.3
We have d = 1.3
Pooled variance = Calculate value of Sd= S^2 = Sqrt [ 43-(13^2/10 ] / 9 = 1.7029
to = d/ (S/n) = 2.414
Critical Value
The Value of |t | with n-1 = 9 d.f is 2.821
We got |t o| = 2.414 & |t | =2.821
Make Decision
Hence Value of |to | < | t | and Here we Do not Reject Ho
p-value :right tail - Ha : ( p > 2.414 ) = 0.01949
hence value of p0.01 < 0.01949,here we reject Ho
ANSWERS
---------------
null, H0: Ud < 0
alternate, H1: Ud > 0
test statistic: 2.414
critical value: reject Ho, if to > 2.821
decision: Do not Reject Ho
p-value: 0.01949