Consider a sample with data values of 10, 20, 12, 17 and 16. Compute the z-score for the first three observations
A clinical trial was conducted to test the effectiveness of a drug for treating insomnia in older subjects. Before treatment, 25 subjects had a mean wake time of 104.0 min. After treatment, the 25 subjects had a mean wake time of 94.7 min and a standard deviation of 22.4 min. Assume that the 25 sample values appear to be from a normally distributed population and construct a 99% confidence interval estimate of the mean wake time for a population with drug treatments
(a) Construct the 99% confidence interval estimate of the mean wake time for a population with the treatment.
(b) What does the result suggest about the mean wake time of 104.0 min before the treatment?
(c) Does the drug appear to be effective?
2.During the first 13 weeks of the
television season, Saturday night
audiences, between 8:00 pm and
12:00 pm, were recorded as
follows: ABC 795 households, CBS
870 households, NBC 989
households, and other channels
546 households. Sponsors want to
know how satisfied the audience of
these channels is to promote their
products.
a.Determine the sample size with
e=.03 and Z=99%.
b.The sample size for the
population with =.03 and K=99%.
c.l explained, which of the
estimated samples would you
recommend to perform?
the evaluation?
Simple Linear Regression - Difference between predicting and estimating?
Here is what my notes say about estimation and prediction:
Estimating the conditional mean
"We need to estimate the conditional mean at a value , so we use as a natural estimator." here we get
with a confidence interval for is
where Where these results are found by looking at the shape of the distribution and at and
Predicting observations
"We want to predict the observation at a value "
Hence a prediction interval is of the form
If the area to the left of x in a normal distribution is 0.346, what is the area to the rig of a?