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Statistics is a branch of applied mathematics dealing with data collection, organization, analysis, interpretation and presentation. Descriptive statistics summarize data. ... In addition to being the name of a field of study, the word "statistics" also refers to numbers that are used to describe data or relationships.
Typology: Assignments
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Question 1 : Use the table/simulation to find the following critical values:
𝑇~𝑡 Distribution: 1 − 𝑃(
𝑑𝑓
) = 0. 05 for 𝑑𝑓 = 5 , 10 , 20 , 30 , 50. How
do these compare to the 0.05 critical values of the Normal distribution?
Question 2: Suppose 𝑋
1
2
6
are six random variables that form a random
sample from the standard normal distribution.
Let 𝑌 = (𝑋
1
2
3
2
4
5
6
2
Find the value of 𝑐 such that the random variable 𝑐𝑌 will follow the chi-square
distribution
Question 3 : Suppose you are looking at treatment and control group differences to
determine the effectiveness of a computer-skills training programme on weekly
wages. The standard deviation of the weekly wages is $15 for both the treatment
and control groups. Now the average weekly wages for the control group is $
and $100+δ for the treatment group. If you are constrained to have 25% of your
observations in the control group and 75% observations in your treatment group,
how large does 𝑁 have to be in order for the probability of 𝑋
𝑇
𝐶
0 is atleast
Note: 𝑋
𝑇
and 𝑋
𝐶
are the sample averages weekly wages of the treatment and
control groups respectively and 𝑁 is the total number of observations in your
experiment that is split between the treatment and control groups. Also assume that
the sample averages are normally distributed.
Question 4 : A random sample of 𝑛 items is to be taken from a distribution with
mean μ and standard deviation 𝜎.
a) Use the Chebyshev inequality to find out the smallest number of items 𝑛 that
must be taken to satisfy:
𝑛
− μ| ≤
b) Use the central limit theorem to find out the smallest number of items 𝑛 that
must be taken to satisfy the above relation in a) approximately.
Question 5 : MLE and MoM estimators:
a) Give the log likelihood function of a sample of 𝑁 iid Poisson random
variables 𝑋
1
𝑁
and solve for the MLE estimator of the parameter λ.
b) Provide the MoM estimator of the parameter λ and compare with the MLE
estimator.
Question 6 : a) Suppose that the ransom variables 𝑋
1
2
𝑛
form a random
sample from the Bernoulli distribution with parameter θ, which is unknown ( 0 ≤
θ ≤ 1 ). For all observed values 𝑥 1
2
𝑛
where each 𝑥
𝑖
is either 0 or 1, what is
the likelihood function? What is the MLE of θ?
b) It is not known what proportion 𝑝 of the purchases of a certain brand of
breakfast cereal are made by women and what proportion is made by men. In a
random sample of 70 purchases of this cereal, it was found that 58 were made by
women and the rest by men. Find the MLE of 𝑝.