/*! 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 6 Blood pressure values are often ... [FREE SOLUTION] | 91Ó°ÊÓ

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Blood pressure values are often reported to the nearest \(5 \mathrm{mmHg}\) ( \(100,105,110\), etc.). Suppose the actual blood pressure values for nine randomly selected individuals are \(\begin{array}{lllllll}118.6 & 127.4 & 138.4 & 130.0 & 113.7 & 122.0 & 108.3 \\\ 131.5 & 133.2 & & & & & \end{array}\) a. What is the median of the reported blood pressure values? b. Suppose the blood pressure of the second individual is \(127.6\) rather than \(127.4\) (a small change in a single value). How does this affect the median of the reported values? What does this say about the sensitivity of the median to rounding or grouping in the data?

Short Answer

Expert verified
a. Original median: 127.4. b. New median: 127.6; the median is slightly sensitive to small changes in one value.

Step by step solution

01

Arrange the Values

First, arrange the blood pressure values in increasing order: \(108.3, 113.7, 118.6, 122.0, 127.4, 130.0, 131.5, 133.2, 138.4\).
02

Identify the Median

There are nine values, an odd number, so the median is the fifth value in the sorted list. From the list \(108.3, 113.7, 118.6, 122.0, 127.4, 130.0, 131.5, 133.2, 138.4\), the median is \(127.4\).
03

Change One Value

Change the blood pressure value of the second individual from \(127.4\) to \(127.6\). This modifies the list to: \(108.3, 113.7, 118.6, 122.0, 127.6, 130.0, 131.5, 133.2, 138.4\).
04

Rearrange the Values

Rearrange the modified list in increasing order again: \(108.3, 113.7, 118.6, 122.0, 127.6, 130.0, 131.5, 133.2, 138.4\).
05

Recalculate the Median

The median will still be the fifth value of the sorted list. In the modified list, the fifth value is now \(127.6\).
06

Analyze Sensitivity

Since the median went from \(127.4\) to \(127.6\) with a small change in one value, this demonstrates that a small change in a single data point slightly affects the median. However, because the values remained sorted in the same order, the median is only slightly sensitive to individual small changes.

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Key Concepts

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

Blood Pressure Analysis
Blood pressure is a critical indicator of cardiovascular health. Understanding how to analyze blood pressure data is essential for accurate health assessments. When analyzing blood pressure data, such as in the provided example, it's common to round measurements to the nearest values like 100, 105, or 110 mmHg. This measurement ranges help in simplifying the data handling process.

However, it's important to be aware that rounding can sometimes obscure smaller changes in data that are clinically significant. These small changes, even by fractions like 0.2 mmHg, might have considerable implications in medical settings. Therefore, accurate measurement and careful handling of blood pressure values form the backbone of proper health monitoring and analysis.
Data Sensitivity
Data sensitivity refers to how changes in input data can impact the results of data analysis. Evaluating sensitivity is crucial in understanding the robustness of statistical measures. In our specific exercise, we noticed that a minor change in blood pressure—by changing a value from 127.4 to 127.6—affected the median of our sample data.

The median, known for its robustness compared to the mean, can still be mildly affected by small changes in values, as shown in the example. Even slight modifications necessitate recalculations to inspect how these influence the outcomes. This provides evidence that while the median might slightly shift, it remains a less vulnerable measure to extreme values compared to other statistical metrics. Nevertheless, such sensitivity should be considered when interpreting results, particularly in fields reliant on precision like healthcare.
Arranging Data
Arranging data is a foundational step in statistical analysis. This process involves organizing data in a logical order before performing any calculations. In our example, we arrange the given blood pressure values in increasing order.

Arranging values helps in identifying patterns and is a preliminary step for calculating the median. By sorting data from the smallest to largest, it becomes easier to pinpoint the central tendency, especially useful for determining the median. In any statistical analysis where the median is of interest, remember that proper arrangement of the data is essential to ensure accurate results.
  • Facilitates easy identification of the median or other metrics.
  • Helps in visualizing the distribution of data across a range.
  • Prevents errors in analysis due to incorrect sequencing.
Always verify the order of data before proceeding with statistical calculations.
Step-by-Step Calculations
Step-by-step calculations ensure clarity and accuracy in data analysis, avoiding potential errors. Let’s go through how this applies to finding the median in the context of our exercise.

1. **Arrange the Data:** Start by organizing the data into increasing order, which makes calculation straightforward. For example, the blood pressure values should be listed from 108.3 to 138.4 mmHg.

2. **Identify the Median:** In a data set with an odd number of values, like our nine blood pressure values, the median is the fifth value. Simply count to locate it accurately.

3. **Check Changes:** When any single data point changes, update your data list and reorder if necessary, ensuring the results reflect any updates.

These steps provide a clear framework for understanding dynamic changes in data and helping in the visualization of their impact on statistical measures like the median. This method not only applies to blood pressure data but is beneficial for various analytical contexts, ensuring precision and consistent results.

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Most popular questions from this chapter

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