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26\. More conclusions In January \(2002,\) two students made worldwide headlines by spinning a Belgian euro 250 times and getting 140 heads - that's \(56 \%\). That makes the \(90 \%\) confidence interval \((51 \%, 61 \%) .\) What does this mean? Are these conclusions correct? Explain. a. Between \(51 \%\) and \(61 \%\) of all euros are unfair. b. We are \(90 \%\) sure that in this experiment this euro landed heads on between \(51 \%\) and \(61 \%\) of the spins. c. We are \(90 \%\) sure that spun euros will land heads between \(51 \%\) and \(61 \%\) of the time. d. If you spin a euro many times, you can be \(90 \%\) sure of getting between \(51 \%\) and \(61 \%\) heads. e. Ninety percent of all spun euros will land heads between \(51 \%\) and \(61 \%\) of the time.

Short Answer

Expert verified
None of the statements A to E correctly interpret the confidence interval from this experiment. This is because a confidence interval gives an estimated range of values which is likely to include an unknown population parameter, not about repeating the experiment or fairness of the coins.

Step by step solution

01

Statement A Analysis

Statement A suggests that between 51 % and 61 % of all euros are unfair. This is not a correct interpretation of the confidence interval in this experiment. A confidence interval is about before-the-fact probabilities attached to a method of computation, not the after-the-fact probabilities attached to a particular realized value. Therefore, the fairness or unfairness of Euro coins in general is not implied by this confidence interval.
02

Statement B Analysis

Statement B indicates that there is a 90 % surety that in this specific experiment this euro landed heads on between 51 % and 61 % of the spins. This interpretation is incorrect. The confidence interval reflects what outcomes we might expect in hypothetical replicas of this experiment, not what happened in this particular realization of the experiment.
03

Statement C Analysis

Statement C expresses a 90 % assurance that spun euros will land heads between 51 % and 61 % of the time. This is a misconstruction of the confidence interval because a confidence interval does not predict the percentage of future spins that will result in heads.
04

Statement D Analysis

Statement D asserts that if one spins a euro many times, there can be a 90 % assurance of getting between 51 % and 61 % heads. This interpretation misconstrues the confidence interval as it only applies to the population proportion, not the proportion in repeated sampling.
05

Statement E Analysis

Statement E posits that 90 percent of all spun euros will land heads between 51 % and 61 % of the time. This is not a correct interpretation of the confidence interval. What we can say from the confidence interval is that we are 90% confident that the true population proportion lies within the given interval, not how individual results will fall within this range in repeated sampling.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Probability Interpretation
Understanding the probability interpretation is crucial when it comes to interpreting the results of experiments and statistical analysis. Probability, in the context of confidence intervals, is the measure of how confident we can be in the results obtained from statistical analysis.

For instance, when we discuss a 90% confidence interval, as seen in the Belgian euro spinning experiment, we're engaging in a probabilistic interpretation. This does not indicate that the observed event (spinning heads) will occur 90% of the time in the future. Rather, it signifies that if we could repeat the same experiment over and over, we expect that the proportion of heads would fall within the confidence interval in 90% of those experiments. It is worth noting that this is not a guarantee, but an expectation based on the statistical method used.

Probabilities provide a framework for making educated guesses about the outcome of an event, based on data and statistical theory, rather than offering certainty about single occurrences or future events.
Statistical Inference
Statistical inference encompasses the processes and methods used to make propositions and draw conclusions about a population based on a sample. The Belgian euro experiment illustrates statistical inference; from the sample of 250 spins, conclusions are drawn about the euro's behavior.

In the world of statistics, we use samples because it is often impractical or impossible to examine an entire population. Through a proper sampling method and statistical procedures like confidence intervals, we infer the population's characteristics from the sample. It's essential to understand that the confidence interval produced from a sample offers an estimated range of values within which we expect the true population proportion to lie with a certain level of confidence.

However, statistical inference goes beyond just the computation; it also includes interpreting and assessing whether the methods and results are appropriate for the hypotheses and the data.
Hypothesis Testing
Hypothesis testing is a formal procedure used by statisticians to test whether a certain hypothesis about a population parameter is likely to be true. This involves stating a null hypothesis, which is a statement of no effect or no difference, and an alternative hypothesis, which is what researchers aim to support.

In the context of the euro experiment, if we conducted a hypothesis test, we might state the null hypothesis as, 'The coin is fair, and the probability of heads is 50%.' Then, based on our experiment results and the corresponding p-value (the probability of finding the observed, or more extreme, results when the null hypothesis is true), we would either reject or fail to reject this null hypothesis.

Hypothesis testing is integral to making decisions and judgments in the presence of variability and uncertainty, allowing researchers to move beyond the data from a sample to broader generalizations.
Population Proportion
The population proportion is a fundamental concept in statistics, representing the part of the population that has a certain attribute. When experimenting with a Belgian euro, we're interested in the true proportion of times a euro lands on heads when spun.

A key point to remember is that the confidence interval constructed from the sample data of 250 spins gives an estimated range for this population proportion. The interval doesn't claim that any single coin, or even a specific subset of euros, will have this exact proportion of heads in future spins. It provides an estimate for the entire population of spins we might observe. The confidence interval conveys the precision of our estimate, which is influenced by the size of the sample and the variability in the data.

Understanding the population proportion within the context of confidence intervals and probability helps in deciphering the scope and limitations of statistical conclusions drawn from experimental data.

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Most popular questions from this chapter

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