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In the July 2007 issue, Consumer Reports examined the calorie content of two kinds of hot dogs: meat (usually a mixture of pork, turkey, and chicken) and all beef. The researchers purchased samples of several different brands. The meat hot dogs averaged 111.7 calories, compared to 135.4 for the beef hot dogs. A test of the null hypothesis that there's no difference in mean calorie content yields a P-value of 0.124 . Would a \(95 \%\) confidence interval for \(\mu_{M e a t}-\mu_{B e e f}\) include \(0 ?\) Explain.

Short Answer

Expert verified
Yes, a 95% confidence interval for the difference in means between caloric content of meat and beef hot dogs would include 0, as the P-value is greater than 0.05 and thus we do not have enough evidence to reject the null hypothesis of no difference.

Step by step solution

01

Understand the P-Value

The P-value is 0.124, which is greater than 0.05. This indicates that the data do not provide enough evidence to reject the null hypothesis, which posits no difference in the average caloric content of the two types of hot dogs.
02

Understand the Confidence Interval

A 95% confidence interval for the difference in means indicates the range of values within which we can be 95% confident that the true difference lies.
03

Include Zero

Since the P-value is greater than 0.05, we lack enough evidence to say the means of the two types of hot dogs are different. Thus, we can't rule out the possibility that the true difference in means could be 0, and the 95% confidence interval would include 0.

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Key Concepts

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

P-value
In the realm of statistics, the P-value is a crucial concept used to determine the strength of evidence against the null hypothesis—essentially a tool to measure whether the observed data are unusual under the assumption that the null hypothesis is true. It quantifies the probability of obtaining test results at least as extreme as the ones observed, assuming that the null hypothesis is accurate. Hence, a lower P-value indicates that there is stronger evidence in favor of the alternative hypothesis.

In the context of the hot dogs' calorie content study, the P-value of 0.124 hints that there is not enough proof to conclude a significant difference in the mean calories between meat and beef hot dogs. Since this P-value exceeds 0.05, which is a commonly used threshold, the null hypothesis cannot be discarded based on this criterion alone. The result implicates that we might observe such a difference (or even a larger one) purely by chance more than 12% of the time when there is actually no difference in reality.
Confidence Interval
The confidence interval (CI) is a range of values, derived from sample statistics, that is likely to include the true value of an unknown population parameter. More specifically, a 95% confidence interval implies that if we were to take 100 different samples and compute a confidence interval for each sample, we would expect about 95 of those intervals to contain the true parameter.

In our hot dog calorie comparison, the 95% confidence interval concerns the difference in mean calorie content between meat hot dogs and beef hot dogs. If this interval contains the value zero, it signifies that there is a high probability—95% to be exact—that the true difference in mean calorie content could be zero, suggesting no difference between the two types of hot dogs. Given the P-value is above 0.05, we infer that the confidence interval probably does include zero, which again does not provide the evidence needed to refute the null hypothesis.
Mean Calorie Content
Mean calorie content is the average amount of calories in a given food item, which in our case, refers to the hot dogs. The mean is calculated by summing the total calories of all samples and dividing by the number of samples. It's an essential measure in nutrition science as it helps consumers understand the energy they can expect to obtain from consuming a product.

In the study at hand, researchers calculated the mean calorie content for meat hot dogs and beef hot dogs separately. Any discovered difference in these means could have implications for consumer choices and health recommendations. However, as indicated by both the P-value and the confidence interval, the statistical evidence does not support a significant difference in mean calorie content between the two types of hot dogs in this particular study.
Statistical Significance
Statistical significance is a determination of whether the observed differences or associations in data are likely due to actual effects rather than mere random variations. It is often judged by the P-value in conjunction with a pre-determined significance level (alpha), with a common choice for alpha being 0.05. If the P-value falls below this threshold, the results are considered statistically significant, leading to the rejection of the null hypothesis.

Translating this to our exercise, because the P-value is 0.124, which is above the conventional alpha value of 0.05, the difference in calorie content between the types of hot dogs is not statistically significant. This indicates that the observed differences could likely be attributed to random sample variability rather than a true difference in calorie content. Thus, in this scenario, we would maintain the null hypothesis and conclude that there is not a statistically significant difference between the calorie content of meat hot dogs and beef hot dogs.

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Most popular questions from this chapter

In Exercise 53 , we saw a \(90 \%\) confidence interval of (-6.5,-1.4) grams for \(\mu_{\text {Meat }}-\mu_{\text {Beef }}\) the difference in mean fat content for meat vs. all-beef hot dogs. Explain why you think each of the following statements is true or false: a. If I eat a meat hot dog instead of a beef dog, there's a \(90 \%\) chance I'll consume less fat. b. \(90 \%\) of meat hot dogs have between 1.4 and 6.5 grams less fat than a beef hot dog. c. I'm \(90 \%\) confident that meat hot dogs average between 1.4 and 6.5 grams less fat than the beef hot dogs. d. If I were to get more samples of both kinds of hot dogs, \(90 \%\) of the time the meat hot dogs would average between 1.4 and 6.5 grams less fat than the beef hot dogs. e. If I tested more samples, l'd expect about \(90 \%\) of the resulting confidence intervals to include the true difference in mean fat content between the two kinds of hot dogs.

Data collected in 2015 by the Behavioral Risk Factor Surveillance System revealed that in the state of New Jersey, \(27.3 \%\) of whites and \(47.2 \%\) of blacks were cigarette smokers. Suppose these proportions were based on samples of 3607 whites and 485 blacks. a. Create a \(90 \%\) confidence interval for the difference in the percentage of smokers between black and white adults in New Jersey. b. Does this survey indicate a race-based difference in smoking among American adults? Explain, using your confidence interval to test an appropriate hypothesis. c. What alpha level did your test use?

Is it a good idea to listen to music when studying for a big test? In a study conducted by some statistics students, 62 people were randomly assigned to listen to rap music, music by Mozart, or no music while attempting to memorize objects pictured on a page. They were then asked to list all the objects they could remember. Here are summary statistics for each group: a. Does it appear that it is better to study while listening to Mozart than to rap music? Test an appropriate hypothesis and state your conclusion. b. Create a \(90 \%\) confidence interval for the mean difference in memory score between students who study to Mozart and those who listen to no music at all. Interpret your interval.

A new vaccine was recently tested to see if it could prevent the painful and recurrent ear infections that many infants suffer from. The Lancet, a medical journal, reported a study in which babies about a year old were randomly divided into two groups. One group received vaccinations; the other did not. During the following year, only 333 of 2455 vaccinated children had ear infections, compared to 499 of 2452 unvaccinated children in the control group. a. Are the conditions for inference satisfied? b. Find a \(95 \%\) confidence interval for the difference in rates of ear infection. c. Use your confidence interval to explain whether you think the vaccine is effective.

There has been debate among doctors over whether surgery can prolong life among men suffering from prostate cancer, a type of cancer that typically develops and spreads very slowly. Recently, The New England Journal of Medicine published results of some Scandinavian research. Men diagnosed with prostate cancer were randomly assigned to either undergo surgery or not. Among the 347 men who had surgery, 16 eventually died of prostate cancer, compared with 31 of the 348 men who did not have surgery. a. Was this an experiment or an observational study? Explain. b. Create a \(95 \%\) confidence interval for the difference in rates of death for the two groups of men. c. Based on your confidence interval, is there evidence that surgery may be effective in preventing death from prostate cancer? Explain.

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