Question

In a randomized double-blind, placebo-controlled trial of children, an herb was tested as a treatment for upper respiratory infections in children. "Days of fever" was one criterion used to measure effects. Among 320 children treated with the herb, the mean number of days with fever was 0.81 with a standard deviation of 1.42 days. Among 372 children given a placebo, the mean number of days with fever was 0.62 with a standard deviation of 1.15 days. Use a 0.05 significance level to test the claim that the herb affects the number of days with fever. Based on these results, does the herb appear to be effective? Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Let population 1 be children treated with the herb.

What are the null and alternative hypotheses for the hypothesis test?

Identify the test statistic:

Identify the P Value:

What is the conclusion based on the hypothesis test?

The P-value is (less than, greater than) the significance level of α=0.05, so (reject, fail to reject) the null hypothesis. There (is, is not) sufficient evidence to support the claim that the fatality rate is higher for those not wearing seat belts.

Answer #1

In a randomized double-blind, placebo-controlled trial of
children, an herb was tested as a treatment for upper respiratory
infections in children. "Days of fever" was one criterion used to
measure effects. Among 309 children treated with the herb, the
mean number of days with fever was 0.91, with a standard deviation
of 1.54 days. Among 370 children given a placebo, the mean number
of days with fever was 0.73 with a standard deviation of 1.24 days.
Use a 0.01 significance...

A randomized, double-blind, placebo-controlled study evaluated
the effect of the herbal remedy Echinacea purpurea in
treating upper respiratory tract infections in 2- to 11-year olds.
Each time a child had an upper respiratory tract infection,
treatment with either echinacea or a placebo was given for the
duration of the illness. One of the outcomes studied was “severity
of symptoms.” A severity scale based on four symptoms was monitored
and recorded by the parents of subjects for each instance of upper...

7. A randomized, double-blind, placebo-controlled study
evaluated the effect of the herbal remedy Echinacea purpurea in
treating upper respiratory tract infections in 2- to 11-year olds.
Each time a child had an upper respiratory tract infection,
treatment with either echinacea or a placebo was given for the
duration of the illness. One of the outcomes studied was “severity
of symptoms.” A severity scale based on four symptoms was monitored
and recorded by the parents of subjects for each instance of...

The herb ginkgo biloba is commonly used as a treatment to
prevent dementia. In a study of the effectiveness of this
treatment, 1545 elderly subjects were given ginkgo and 1524 elderly
subjects were given a placebo. Among those in the ginkgo treatment
group, 246 later developed dementia, and among those in the placebo
group, 277 later developed dementia (based on data from “Ginkgo
Biloba for Prevention of Dementia,” by DeKosky et al., Journal of
American Medical Association, Vol. 300, No....

A study was done using a treatment group and a placebo group.
The results are shown in the table. Assume that the two samples are
independent simple random samples selected from normally
distributed populations, and do not assume that the population
standard deviations are equal. Complete parts (a) and (b) below.
Use a 0.05 significance level for both parts.
Treatment
Placebo
u
u1
u2
n
34
30
x
2.34
2.62
s
0.58
0.95
1. The test statistic is _____ (round...

In a randomized controlled trial, insecticide-treated bed nets
were tested as a way to reduce headaches Among 343 children who
used the bed nets, 15 developed headaches. Among 294 infants not
using bed nets, 27 developed headaches. Use a 0.01 significance
level to test the claim that the incidence of headaches is lower
for children who use the bed nets. Do the bed nets appear to be
effective?

Q. 11
A study of seat belt use involved with children who were
hospitalized after motor vehicle crashes. For a group of 121
children who were wearing seat belts, the number of days in
intensive care units (ICU) has a mean of 0.83 and a standard
deviation of 1.77. For a group of 156 children who were not wearing
seat belts, the number of days spent in ICUs has a mean of 1.39 and
a standard deviation of 3.06.
a. Use...

A study was done using a treatment group and a placebo group. The
results are shown in the table. Assume that the two samples are
independent simple random samples selected from normally
distributed populations, and do not assume that the population
standard deviations are equal. Complete parts (a) and (b) below.
Use a
0.10
significance level for both parts.
Treatment
Placebo
mu
mu 1
mu 2
n
29
40
x overbar
2.34
2.69
s
0.82
0.52
a. Test the claim...

A study was done using a treatment group and a placebo group.
The results are shown in the table. Assume that the two samples are
independent simple random samples selected from normally
distributed populations, and do not assume that the population
standard deviations are equal. Complete parts (a) and (b) below.
Use a 0.05 significance level for both parts.
Treatment
Placebo
μ
μ 1
μ 2
n
26
30
x̅
2.34
2.61
s
0.96
0.66
Test the claim that the...

The herb ginkgo biloba is commonly used as a treatment to
prevent dementia. In a study of its effectiveness, 1544 elderly
subjects were given ginkgo and 1543 elderly subjects were given a
placebo. Anong those in the ginkgo group, 250 later developed
dementia, and among those in the placebo group, 296 developed
dementia. Use a 0.05 significance level to test the claim that
ginkgo is effective in preventing dementia. Based on your results,
is ginkgo effective in preventing dementia?
TYPE...

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