Unformatted text preview: is an interval containing the most believable values for a parameter. The probability
that this method produces an interval that contains the parameter is called the conﬁdence level. This
is a number chosen to be close to 1, most commonly 0.95. Palm estimate —r—\‘s—+—— (———>
Confidence interval The‘ measures how accurate the piont estimate is likely to be in estimating a. parameter.
It is a multiple of the standard error of the sampling distribution of the estimate, such as z(se). ME ME
(———} —i—i—]——— ME  margin of error Therefore, the conﬁdence interval is of the form [point estimate :l: margin of error]. In this section, we learn how to construct a conﬁdence interval for a population proportion. The procedure
used is as given below. e \— ue Hz dependsonteh conﬁdence level of interest. For the commonly used conﬁdence levels 95%,
90%, and 99%, the value of 2 equals 1.96, 1.65 and 2.58 respectively. The margin of error is given by me = 2(56). For the above conﬁdence interval to be valid, it is required that both 7113 and n(1 — 13) are at least
15. r“ A survey found that 89% of a random sample of 1024 American adults approved of cloning
endangered animals. Find the margin of error and the conﬁdence interval for this survey if we want 90% conﬁdence in our estimate of the percentage of American adults who approve of cloning endangered
animals. ...
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 Spring '08
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