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The article "Doctor Dogs Diagnose Cancer by Sniffing It Out鈥 (Knight Ridder Newspapers, January 9, 2006) reports the results of an experiment described in the journal Integrative Cancer Therapies. In this experiment, dogs were trained to distinguish between people with breast and lung cancer and people without cancer by sniffing exhaled breath. Dogs were trained to lay down if they detected cancer in a breath sample. After training, dogs' ability to detect cancer was tested using breath samples from people whose breath had not been used in training the dogs. The paper states "The researchers blinded both the dog handlers and the experimental observers to the identity of the breath samples." Explain why this blinding is an important aspect of the design of this experiment.

Short Answer

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Blinding is an important aspect in this experiment to eliminate any external influence or bias that might be introduced by the dog handlers or the experimental observers. By not knowing from whom the breath samples were taken (people with or without cancer), neither the dog handlers nor the observers can influence the dogs actions or interpret the dogs responses based on their knowledge of the samples, thus ensuring objectivity and reliability of the results.

Step by step solution

01

Understanding Blinding

Blinding in an experiment refers to withholding information about the test and control groups from the people who interact with the subjects (participants) of the experiment. This is done to prevent knowledge of the group assignments from influencing the behavior of the experiment administrators and thus skewing the results.
02

Understanding the Purpose of Blinding

The purpose of blinding in an experiment is to eliminate bias. Bias in an experiment can lead to incorrect results and interpretations. For example, if dog handlers knew which samples were from people with cancer and which were not, they might consciously or unconsciously act differently, influencing the dog's behavior.
03

Applying to the Given Experiment

In the given experiment, dogs were trained to distinguish breath samples from people with cancer and without cancer. Blinding the dog handlers and the experimental observers ensures that they don't know whether the samples given to the dogs are from persons with cancer or without. As a result, their actions or reactions won't influence the dogs' senses.

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Key Concepts

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

Blinding in Experiments
Blinding is a fundamental technique used in experimental design aimed at reducing bias and ensuring the integrity of research outcomes. In the context of the experiment detailed in 'Doctor Dogs Diagnose Cancer by Sniffing It Out', blinding plays a crucial role in maintaining objectivity. When experiment handlers and observers are 'blinded', they are unaware of which samples are controls (non-cancer) and which are tests (cancer), eliminating any possibility of their expectations or preconceived notions affecting the behavior of the dogs or the interpretation of the dogs' reactions.

This is particularly important because any cues or subconscious signals from the handlers could inadvertently train the dogs to respond to the handlers' behavior instead of the breath samples. By removing this variable, the researchers can be more confident that the dogs are genuinely detecting cancer based on scent alone and not due to human influence. In practice, there might be single or even double-blinding where the administrator or both the administrator and the participants are unaware of the group assignments. The blinding in this experiment is a prime example of meticulous design in research methodology to harvest unbiased and valid results.
Bias Elimination
Eliminating bias is critical in any investigation where the aim is to establish a factual conclusion. Bias can creep into experiments in numerous ways, such as through the selection of participants, the administration of interventions, or the measurement of outcomes. In the case of the cancer-detecting dogs, bias could be introduced if the handlers were able to guess which samples were cancerous and which were not and convey their biases through body language or other subtle cues. The experimental design must therefore incorporate strategies to mitigate these potential biases.

Other techniques alongside blinding may include randomization of sample presentation, using standardized procedures for interactions, and having multiple blind observers to cross-validate the results. These methods help to ensure that the findings of an experiment are attributable to the effects of the variables being tested rather than to external biases or systemic errors.
Statistical Analysis
Once the data is collected through well-designed experiments like the one with cancer-detecting dogs, statistical analysis becomes the backbone for interpreting the results. It involves applying mathematical principles to determine if the findings offer significant evidence that can be generalized beyond the experimental conditions. For this experiment, statistical analysis would involve calculating the rate at which dogs correctly identify cancerous samples compared to false positives and negatives, determining the sensitivity and specificity of the dogs' detection abilities.

Advanced statistical techniques, such as logistic regression or receiver operating characteristic (ROC) curves, might be utilized to understand the true performance of the dogs in medical diagnostics. This process includes examining the confidence intervals, the probability of type I and type II errors, and the power of the study 鈥 all of which contribute to the robustness and reliability of the research conclusions.

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Most popular questions from this chapter

The report "Comparative Study of Two Computer Mouse Designs" (Cornell Human Factors Laboratory Technical Report RP7992) included the following description of the subjects used in an experiment: Twenty-four Cornell University students and staff ( 12 males and 12 females) volunteered to participate in the study. Three groups of 4 men and 4 women were selected by their stature to represent the 5 th percentile (female \(152.1 \pm 0.3 \mathrm{~cm},\) male \(164.1 \pm 0.4 \mathrm{~cm}), 50\) th percentile (female \(162.4 \pm 0.1 \mathrm{~cm},\) male \(174.1 \pm 0.7 \mathrm{~cm}),\) and 95 th percentile (female \(171.9 \pm 0.2 \mathrm{~cm},\) male \(185.7 \pm 0.6 \mathrm{~cm}\) ranges \(\ldots\) All subjects reported using their right hand to operate a computer mouse. This experimental design incorporated direct control and blocking. a. Are the potential effects of the extraneous variable stature (height) addressed by blocking or direct control? b. Whether the right or left hand is used to operate the mouse was considered to be an extraneous variable. Are the potential effects of this variable addressed by blocking or direct control?

Red wine contains flavonol, an antioxidant thought to have beneficial health effects. But to have an effect, the antioxidant must be absorbed into the blood. The article "Red Wine is a Poor Source of Bioavailable Flavonols in Men" (The journal of Nutrition [2001]: \(745-748\) ) describes a study to investigate three sources of dietary flavonol-red wine, yellow onions, and black tea-to determine the effect of source on absorption. The article included the following statement: We recruited subjects via posters and local newspapers. To ensure that subjects could tolerate the alcohol in the wine, we only allowed men with a consumption of at least seven drinks per week to participate \(\ldots\) Throughout the study, the subjects consumed a diet that was low in flavonols. a. What are the three treatments in this experiment? b. What is the response variable? c. What are three extraneous variables that the researchers chose to control in the experiment?

The article "Workers Grow More Dissatisfied" in the San Luis Obispo Tribune (August 22, 2002\()\) states that "a survey of 5000 people found that while most Americans continue to find their jobs interesting, and are even satisfied with their commutes, a bare majority like their jobs." This statement was based on the fact that only 51 percent of those responding to a mail survey indicated that they were satisfied with their jobs. Describe any potential sources of bias that might limit the researcher's ability to draw conclusions about working Americans based on the data collected in this survey.

A study of college students showed a temporary gain of up to 9 IQ points after listening to a Mozart piano sonata. This conclusion, dubbed the Mozart effect, has since been criticized by a number of researchers who have been unable to confirm the result in similar studies. Suppose that you wanted to see whether there is a Mozart effect for students at your school. a. Describe how you might design an experiment for this purpose. b. Does your experimental design include direct control of any extraneous variables? Explain. c. Does your experimental design use blocking? Explain why you did or did not include blocking in your design. d. What role does random assignment play in your design?

Asthma is a chronic lung condition characterized by difficulty in breathing. Some studies have suggested that asthma may be related to childhood exposure to some animals, especially dogs and cats, during the first year of life (鈥淓xposure to Dogs and Cats in the First Year of Life and Risk of Allergic Sensitization at 6 to 7 Years of Age," Journal of the American Medical Association [2002]: 963-972). Some environmental factors that trigger an asthmatic response are (1) cold air, (2) dust, (3) strong fumes, and (4) inhaled irritants. a. Write a set of questions that could be used in a survey to be given to parents of young children suffering from asthma. The survey should include questions about the presence of pets in the first year of the child's life as well as questions about the presence of pets today. Also, the survey should include questions that address the four mentioned household environmental factors. b. It is generally thought that low-income persons, who tend to be less well educated, have homes in environments where the four environmental factors are present. Mindful of the importance of comprehension, can you improve the questions in Part (a) by making your vocabulary simpler or by changing the wording of the questions? c. One problem with the pet-related questions is the reliance on memory. That is, parents may not actually remember when they got their pets. How might you check the parents' memories about these pets?

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