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STA 2381- Statistics Exam | Questions with Correct Verified Answers
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STA 2381- Statistics Exam | Questions with Correct Verified Answers
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STA 2381- Statistics Exam | Questionswith Correct Verified Answers
T/F: A point estimate is preferred over an interval estimate from a statistical point of view -
ANSWER False
(point estimate only gives you data at that specific point, while interval would give a
accurate estimate because it can be averaged)
T/F: All density functions of random variable are symmetric and unimodal - ANSWER False
T/F: Increasing the confidence interval decreases the width of the interval estimate, given
that the sample data remains the same - ANSWER False
(increasing the CI, increases the width of the interval estimate)
T/F: Increasing the confidence interval increases the width of the interval estimate, given
that the sample data remains the same - ANSWER True
T/F: Statistical Inference permits us to draw conclusions concerning a population and its
population parameters based on sample data - ANSWER True
Independent Events - ANSWER The occurrence of A does NOT affect the occurrence of B
Mutually Exclusive Events - ANSWER Event A and B cannot occur at the same time
(cannot overlap). They cannot have anything in common.
, Can Independent Events occur at the same time as Mutually Exclusive Events - ANSWER NO.
NEVER.
Law of total probability - ANSWER An event can be written as the sum of disjoint events
(Picture Event B as divided into sections Ai)
does disjoint = mutually exclusive ? - ANSWER YES.
DISJOINT=MUTUALLY EXCLUSIVE
T/F: The width of a confidence interval decreases as the sample size increases for a fixed
confidence interval, provided the sample standard deviation remains constant - ANSWER True
(as sample size increases, CI decreases.
As sample size decreased, CI increases)
T/F: Confidence intervals give no information regarding the precision of an estimator - ANSWER
False
precision of an estimator is measured through confidence intervals
T/F: The width of a confidence interval for the population mean depends only on the
parameter value it is attempting to estimate - ANSWER confidence interval only depends on
-t-value
-(sample standard deviation=sample standard error)
doesn't depend on parameter at all
(if we knew the parameter, we wouldn't have to calculate the confidence interval at all)
What shape is the population density function? - ANSWER The density function can be any
shape as long as it isn't negative
Random sampling - ANSWER every element in the population is equally likely to be sampled
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