Whenever p = 0.15 , the binomial distribution will
always be symmetric
Be symmetric only if n is large.
Be right-skewed
Be left-skewed.
A financial analysis is presented with information on the past records of 60
start-up companies and told that in fact only 3 of them have managed to
become highly successful. He selected 3 companies from this group as the
candidates for success. To analyze his ability to spot the companies that
will eventually become highly successful, he will use what type of
probability distribution?
binomial distribution
Poisson distribution
normal distribution
hypergeometic distribution
Concerning random sampling, choose the incorrect description from the
followings:
A sample unit in a population may have unequal probability to be
selected.
Sampling error may be reduced by choosing more sampling units.
It is an objective sampling technique.
The estimation of population parameters from statistics can be unbiased.
Concerning median and mode, choose the incorrect description from the
followings:
the median of the four data, (1, 2, 3, 4), is 2.5
The median of the five data, (2, 1, 2, 1, 1), is 1
The mode of the four data. (1, 2, 3, 4), is 4
The mode of the four data, (1, 2, 1, 2) are 1 and 2
To compare the failure rate (i.e. the proportion of the score below 60 points)
of statistics course between classes A and B, following data are collected:
the average scores are 75 and 72 points, the standard deviations are 7.5
and 4 points for the classes A and B respectively. Choose the correct
description from the followings:
The failure rate of the class A is higher.
The failure rate of the class B is higher
The two classes have the same failure rate.
There is insufficient data to justify.
The defective rate for a product is 0.1 consistently. We choose 4 products
randomly and independently for inspection. Choose the correct description
on population parameters or the shape of the probability of the number of
defects:
The shape is skewed to the left
The shape is symmetrical
The mode is 0.
The median is greater than the average
For the length of a product, the average and the standard deviation are
specified to be 100cm and 4cm, respectively. We choose 4 products for
inspection every 30 minutes. The tolerance limits are set 4cm away from
the mean of the average. According to the empirical rule for a normal
distribution, what is the probability between the tolerance limits?
0.9974
0.9772
0.9544
0.6826
Because there exists strong competition among 4 candidates for presidency,
one of the four candidates asks a survey company to implement a survey of
support with a marginal error of 2.5%. Based on the previous experience,
the candidate possesses the rate of support between 20% and 30%. At the
level of confidence of 0.95 ( z0.975 = 1.96 , i.e. Pr(Z <= 1.96) = 0.975 ), what is
the conservative sample size to be chosen?
984
1291
1537
2017
To test the difference between the means of two samples, choose the
incorrect description from the followings:
Random sampling has to be used for both independent and related
sampling.
If the two populations are normal distributions with two unknown
variances and are sampled independently, the sampling distribution is
normal.
In case one of the population distribution is distribution-free with a
small sample size, e.g., less than 10, for a related sampling, a signed
test may be used.
If the two populations are normal distributions with two unknown
variances and are relation-sampled, the sampling distribution is a
student distribution.
To test population variances with normal distributions for one-sample
testing, choose the incorrect description from the followings:
For a one-sample test, a chi-square distribution can be used
For a two-sample test, an F distribution can be used
A chi-square distribution has the degree of freedom equal to the sample
size minus one
An F distribution has the degree of freedom equal to the summation of
the two sample sizes minus one
(A)What are the values of (a), (b), and (c)? (1% each)at the 0.05 level of significance:
(B)Is there an interaction between service center and VCR brand? What
conclusion can you make regarding on the interaction effect (5%)
(C)Plot a graph of mean service time for each service center for each VCR
brand. Please mark the cell means in your plot. (10%)
(D)What conclusions can you reach concerning mean service time? (4%)
What is the difference between “independent samples” and “related
samples”? Please given an example for each. (5%)
What are the differences between regression analysis and correlation
analysis? How to determine whether regression analysis or correlation
analysis is more proper for one research analysis? (10%)
What is multicollinearity? What impacts will multicollinearity cause on
regression models? How to avoid such impacts? (12%)
List the steps for stepwise regressions. What are the major differences
between stepwise regression methods and stagewise regression methods?
(10%)
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