ShmoopTube

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Here's your shmoop du jour, brought to you by Interval Estimates.

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Although honestly, if you're a daredevil looking to leap an interval on your bike... you're

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going to want more than an estimate.

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Which of the following statements is true? 

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And here are the potential answers...

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We're given four statements...

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...and we need to find the one that ain't messing with us.

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The first statement says that a confidence interval is a point estimate.

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A confidence interval is an estimate of a range of values within which we would find

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repeated sample means.

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For example, a 90% confidence interval would mean that repeated sampling

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would result in 90% of the sample means falling within the interval.

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Therefore, it is not a point estimate. Rather, it is an interval estimate.

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And Statement 1 is false.

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Statement 2 says that a population proportion is a point estimate.

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Again, we have to know what a population proportion is. It is the proportion of a set of data

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that fulfills a certain criteria.

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For example, the population proportion of people who eat fried ants at least once every

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week out of 200 people in the population is a number we can actually calculate.

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However, there's no estimation when we find this, so it isn't an estimate at all.

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The first two statements are false, so we can eliminate choices A, B, and D.

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Statement 3 says that a sample mean is a point estimate.

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Remember that a sample mean is a single value that estimates the middle of a set of data.

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That one value is a point. Therefore, this statement is true.

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Finally, our last statement says that an interval estimate gives more detail about the uncertainty

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of the estimate than a point estimate.

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This is intuitively true, as simply seeing a mean or median

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tells us nothing about the uncertainty of the data.

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Whereas when we're given a confidence interval, we know a lot about how certain the data is.

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A 99% confidence interval lets us know that 99% of sample means taken will fall within

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the range of the interval.

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Since both statement 3 and 4 are true, we know our answer is (E).

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As in, "Evil Knievel's big moment."

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