91Ó°ÊÓ

It is very inconvenient, to say the least, when sailors get seasick, so Captain McIntosh thought he should try out the latest remedy, 'Sicko' pills. He bought 200 pills (1 for each member of his crew), and 200 others that looked exactly the same but which were made of pure lactose (milk sugar). He would use the latter as a control, for he knew that they had no specific effect on seasickness. He put all the pills in his medicine cupboard, and waited for a storm. During the first storm, Captain McIntosh did nothing except note the names of the 30 men (out of 200 , remember) who became seasick. At the first warning of the next storm, he got each and every man aboard to swallow a lactose pill (he didn't tell anyone what they were or what they were for), and again he noted the names of those who became sick. Finally, when the next storm approached, he gave each man a 'Sicko' pill, and again noted the results. All 3 storms being similar in severity and duration, he felt it was quite fair to compare the results of each storm with each other. So he sorted out the results and found - 15 men were sick only when they took no pill. 3 other men were sick only when they took a 'Sicko' pill. 1 other man was sick only when he took a lactose pill. 8 other men were sick both when they took no pill, and when they took a lactose pill. 4 other men were sick both when they took no pill, and when they took a 'Sicko' pill. 3 other men were sick both when they took a lactose pill, and when they took a 'Sicko' pill. 3 other men were sick on all 3 occasions. Can you tell - a) Was there a significant difference between the numbers of men seasick during the 3 storms? b) How could this investigation have been planned so that it would have remained valid if the storms had proved unequal in severity?

Step by step solution

01

Organize the data in a table

To better visualize and analyze the information, let's organize it into a table. The rows of the table will correspond to the three treatments (no pill, lactose pill, and 'Sicko' pill), whereas the columns will represent the different illnesses states observed (ill during any single storm, ill during two storms, ill during all three storms). Table: | |Ill-1 Storm|Ill-2 Storms|Ill-3 Storms| |:--------------:|:---------:|:----------:|:----------:| |No Pill | 15 | 8 + 4 = 12 | 3 | |Lactose pill | 1 | 8 + 3 = 11 | 3 | |'Sicko' pill | 3 | 4 + 3 = 7 | 3 |

02

Compare the number of men sick during the 3 storms

The total numbers of sick sailors during each storm (sum of each row) can be calculated as follows: No pill: 15 + 12 + 3 = 30 Lactose pill: 1 + 11 + 3 = 15 'Sicko' pill: 3 + 7 + 3 = 13

03

Answer to question (a)

Based on the numbers, there is a significant difference between the number of men seasick during the three storms: - more sailors became sick during the storm with no pill (30) compared to those who took the lactose pill (15) or the 'Sicko' pill (13) - The 'Sicko' pill appears to be the most effective, as the fewest sailors (13) got seasick.

04

Answer to question (b)

In order to account for the possibility that the storms may not be equal in severity, the investigation could have been designed differently. One would use a randomized controlled trial design where the sailors would be randomly divided into three groups: 1. Group 1: Participants receive no pill. 2. Group 2: Participants receive a lactose pill. 3. Group 3: Participants receive a 'Sicko' pill. Each group would experience the same storm, so that the severity and duration of the storm would be the same for everyone. Then, in the following storms, the groups would swap their treatments, making sure to washout the prior treatment effect on each sailor before the next storm for an equal comparison. The main idea here is to ensure that each group experiences the same storm so that any differences between groups can be attributed to the different treatments, rather than differences in the severity of the storms.

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Key Concepts

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

Control Group

A control group is essential in experiments to establish a baseline for comparison. This group does not receive the treatment being tested, instead getting a placebo or no treatment. In the case of Captain McIntosh's seasickness study, the sailors who received the lactose pills constituted the control group. Lactose pills were selected because they are known not to affect seasickness, thus serving as a neutral comparison.
The purpose of the control group is to provide a standard against which the effects of the 'Sicko' pills can be measured. By comparing the seasickness rates among sailors who did not receive the 'Sicko' pill versus those who did, Captain McIntosh could gauge the effectiveness of the pills.
Using a control group helps to identify the true effect of the intervention, ensuring that any changes observed are due to the treatment itself and not other variables. Once compared, this data can show if the treatment has a significant positive impact on preventing seasickness, as indicated by fewer sailors becoming ill with the 'Sicko' pill as opposed to the control group with lactose pills.

Randomized Controlled Trial

A randomized controlled trial (RCT) is a scientific study design that helps to minimize bias in results by randomly assigning participants to different groups. In Captain McIntosh's study, although he used all types of pills on the same crew under different storm conditions, a more robust method would involve random assignment.
To conduct an RCT, sailors could have been randomly divided into three groups:

• Group 1: Receives no treatment or no pill.
• Group 2: Receives the placebo or lactose pill.
• Group 3: Receives the 'Sicko' pill.

Each group undergoes the same conditions concurrently, like experiencing the same storm, which ensures that variations in seasickness are due to the treatment and not other factors like storm severity.
Randomization is crucial as it helps control for confounding variables—those other than the treatment that might influence results. If conducted properly, an RCT can accurately determine the efficacy of the 'Sicko' pill on preventing seasickness by ensuring that each treatment's effects are fairly compared under similar conditions.

Seasickness Research

Seasickness research focuses on understanding and finding ways to prevent or alleviate motion sickness caused by maritime travel. Such studies are essential for maintaining the well-being of those who spend significant time at sea, like sailors and naval officers. Captain McIntosh's experiment attempts to contribute to this body of knowledge by testing the effectiveness of 'Sicko' pills as a potential remedy.
Key elements of successful seasickness research include:

• Rigorous testing procedures like control groups and RCTs.
• Consistency in experimental conditions to ensure reliable data.
• Thorough data analysis to determine the effectiveness of treatments.

By ensuring these methodologies are in place, researchers can accurately determine how well a treatment works. In Captain McIntosh's case, by using a consistent severity of storms for each trial phase, he aimed to make fair comparisons between treatments.
Research into seasickness not only helps improve the quality of life on sea voyages but also informs the development of pharmaceuticals and other interventions that can mitigate symptoms. It highlights the necessity for controlled experimentation to produce reliable and applicable results.