Table of contents
- 1. Intro to Stats and Collecting Data55m
- 2. Describing Data with Tables and Graphs1h 55m
- 3. Describing Data Numerically1h 45m
- 4. Probability2h 16m
- 5. Binomial Distribution & Discrete Random Variables2h 33m
- 6. Normal Distribution and Continuous Random Variables1h 38m
- 7. Sampling Distributions & Confidence Intervals: Mean1h 3m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 12m
- 9. Hypothesis Testing for One Sample1h 1m
- 10. Hypothesis Testing for Two Samples2h 8m
- 11. Correlation48m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 20m
- 14. ANOVA1h 0m
3. Describing Data Numerically
Median
Problem 3.r.1a
Textbook Question
Reported and Measured Heights Listed below are self-reported heights of males aged 16 and over and their corresponding measured heights (based on data from the National Health and Nutrition Examination Survey). All heights are in inches. First find the differences (reported height–measured height), and then use those differences to find the (a) mean, (b) median, (c) mode,


1
Step 1: Calculate the differences between the reported heights and measured heights for each individual. For each pair of values, subtract the measured height from the reported height. For example, for the first pair, the difference is 68.0 - 67.9 = 0.1.
Step 2: List all the calculated differences. These differences will be used to compute the mean, median, and mode.
Step 3: To find the mean, sum all the differences and divide by the total number of differences. Use the formula: \( \text{Mean} = \frac{\text{Sum of differences}}{\text{Number of differences}} \).
Step 4: To find the median, arrange the differences in ascending order and identify the middle value. If there is an even number of differences, take the average of the two middle values.
Step 5: To find the mode, identify the difference value(s) that appear most frequently in the list. If no value repeats, there is no mode.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Mean
The mean is the average of a set of values, calculated by summing all the values and dividing by the number of values. In this context, it will be used to find the average difference between reported and measured heights, providing insight into the overall tendency of self-reported heights compared to actual measurements.
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Median
The median is the middle value in a sorted list of numbers. If the list has an even number of observations, the median is the average of the two middle numbers. This measure is particularly useful in this scenario as it helps to understand the central tendency of the differences without being affected by extreme values.
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Mode
The mode is the value that appears most frequently in a data set. In the context of the height differences, identifying the mode can reveal the most common discrepancy between reported and measured heights, which can be important for understanding patterns in self-reporting accuracy.
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