/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 3 Marcie conducted a study of the ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

Marcie conducted a study of the cost of breakfast cereal. She recorded the costs of several boxes of cereal. However, she neglected to take into account the number of servings in each box. Someone told her not to worry because she just had some sampling error. Comment on that advice.

Short Answer

Expert verified
The issue is not sampling error; Marcie's study lacks validity due to omitted variable bias, not randomness in samples.

Step by step solution

01

Understanding the Problem

Marcie conducted a study to analyze the cost of breakfast cereal. However, she made a mistake by not considering the number of servings in each box, which is a crucial factor in evaluating the cost-effectiveness of each brand given their different serving sizes.
02

Defining Sampling Error

Sampling error refers to the discrepancy between a sample statistic and its corresponding population parameter due to using a subset (sample) rather than the entire population. It generally describes issues that arise from using samples instead of entire populations in statistical analysis.
03

Assessing the Concern

In Marcie's case, her problem is not due to sampling error. The issue arises from the failure to account for the number of servings, which is a bias or confounding variable in the analysis rather than an error related to randomness in sampling.
04

Explaining the Misdirection

The advice given to Marcie to not worry about sampling error is misguided because the core issue in her study is the omission of a key variable (number of servings), which affects the validity of the findings, rather than typical sampling error.
05

Conclusion on Reliability

Marcie should adjust her study to include servings per box in her analysis to ensure her conclusions accurately reflect cost per serving rather than just the box price, as these factors significantly impact the study outcomes.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Cost Analysis
When conducting a cost analysis, it is crucial to examine all factors that can impact the overall cost conclusion. In the case of Marcie's cereal study, simply looking at the box price would not give a complete or accurate picture of the value provided by each box of cereal. One essential element Marcie initially overlooked was the number of servings per box.

Cost analysis involves breaking down and assessing all the components that factor into the cost of a product. This means:
  • Evaluating cost in terms of fixed and variable elements.
  • Considering both macro and microeconomic factors.
  • Analyzing cost-effectiveness or cost per unit.
In cereal analysis, accounting for costs per serving is pivotal because not all boxes provide the same number of servings. A box that is slightly more expensive but offers more servings may actually be more cost-effective than a cheaper, smaller box. Thus, true cost effectiveness is determined by understanding how much each serving costs, rather than the whole box price itself. By including servings, Marcie can calculate the cost per serving and gain more accurate, data-driven insights into which cereal offers the best value.
Confounding Variable
A confounding variable is any outside influence that changes the effect of a dependent and independent variable. In statistical research, it's critical to identify confounding variables to avoid misleading results. Applying this to Marcie's cereal study, the number of servings per box is a classic example of a confounding variable that can distort the results if not properly addressed.

Confounding occurs when an omitted variable ables the relationship you are studying. In Marcie's scenario, the omission means her analysis risks showing incorrect cost conclusions. This is because:
  • Without considering servings, the analysis only reflects box prices rather than price per unit of consumption.
  • This omission might lead to incorrect boil-down answers on which cereal is more economical.
Recognizing and adjusting for confounding variables helps in:
  • Achieving more accurate and authentic results.
  • Improving the reliability of conclusions.
  • Ensuring all interpretations of data reflect real relationships rather than misleading artifacts.
Thus, in Marcie's study, correcting for this oversight will help genuinely determine cost-worth by allowing a precise comparison of cereal box prices relative to the value they offer per serving.
Statistical Analysis
Statistical analysis involves using statistical processes to evaluate and interpret data. It's a comprehensive approach to infer conclusions and inform decisions based on quantitative data. Marcie's study on cereal costs, when enhanced by statistical analysis, would allow a deeper and more meaningful insight into the real value of cereal options.

For effective statistical analysis, Marcie should:
  • Collect comprehensive data that covers all necessary variables (e.g., servings per box).
  • Use descriptive statistics to summarize basic features of the data such as mean, median, and mode.
  • Apply inferential statistics to draw conclusions about the population based on the sample data.
Honing in on these principles means Marcie can transform raw data into understandable and actionable insights. Statistical analysis aids in correcting potential biases like sampling errors or confounding variables by ensuring validity and reliability in research findings.

Ultimately, by leveraging statistical analysis in her study, Marcie moves beyond simple observations. She gains the sophistication needed to make data-driven decisions that reflect true cost implications and guide consumers on value-based choices.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Use a random-number table to simulate the outcomes of tossing a quarter 25 times. Assume that the quarter is balanced (i.e., fair).

Surveys: Manipulation The New York Times did a special report on polling that was carried in papers across the nation. The article pointed out how readily the results of a survey can be manipulated. Some features that can influence the results of a poll include the following: the number of possible responses, the phrasing of the questions, the sampling techniques used (voluntary response or sample designed to be representative), the fact that words may mean different things to different people, the questions that precede the question of interest, and finally, the fact that respondents can offer opinions on issues they know nothing about. (a) Consider the expression "over the last few years." Do you think that this expression means the same time span to everyone? What would be a more precise phrase? (b) Consider this question: "Do you think fines for running stop signs should be doubled?" Do you think the response would be different if the question "Have you ever run a stop sign?" preceded the question about fines? (c) Consider this question: "Do you watch too much television?" What do you think the responses would be if the only responses possible were yes or no? What do you think the responses would be if the possible responses were "rarely," "sometimes," or "frequently"?

Consider the students in your statistics class as the population and suppose they are seated in four rows of 10 students each. To select a sample, you toss a coin. If it comes up heads, you use the 20 students sitting in the first two rows as your sample. If it comes up tails, you use the 20 students sitting in the last two rows as your sample. (a) Does every student have an equal chance of being selected for the sample? Explain. (b) Is it possible to include students sitting in row 3 with students sitting in row 2 in your sample? Is your sample a simple random sample? Explain. (c) Describe a process you could use to get a simple random sample of size 20 from a class of size \(40 .\)

What is the average miles per gallon (mpg) for all new hybrid small cars? Using Consumer Reports, a random sample of such vehicles gave an average of \(35.7 \mathrm{mpg.}\) (a) Identify the variable. (b) Is the variable quantitative or qualitative? (c) What is the implied population?

Suppose you are assigned the number \(1,\) and the other students in your statistics class call out consecutive numbers until each person in the class has his or her own number. Explain how you could get a random sample of four students from your statistics class. (a) Explain why the first four students walking into the classroom would not necessarily form a random sample. (b) Explain why four students coming in late would not necessarily form a random sample. (c) Explain why four students sitting in the back row would not necessarily form a random sample. (d) Explain why the four tallest students would not necessarily form a random sample.

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.