ng goals
Interpret margin of error and confidence intervals for real-life scenarios.
Example: Average weight
Over the past 20 years, the Centers for Disease Control (CDC) has reported a significant increase in obesity in the United States. Because recording and tracking the weight of every person in the country is impossible, researchers rely on collecting data through surveys or asking individuals questions through the phone, online, or on paper. Because data is based on a sample, a margin of error will exist.

Gallup's annual Health and Healthcare survey has asked Americans about their weight every year for several decades. In 2011, Gallup noted that the self-reported weight of both men and women were up by 20 pounds since 1990.

Figure 4.5.1: Graph of the self-reported weight vs. ideal weight for men and women from 1991 - 2011.
Two graphs showing the self-reported weight vs ideal weight for men and women from 1991 to 2011. For both graphs, the self-reported weight is higher than the ideal weight. The weights for both men and women increase as the year increases.
"For the total sample of national adults, the results show with 95% confidence that the maximum margin of sampling error is ±4 percentage points.

Gallup surveyed 532 men and 480 women. For results based on men, one can say with 95% confidence that the maximum margin of sampling error is ±5 percentage points. For results based on women, one can say with 95%
confidence that the maximum margin of sampling error is ±6 percentage points."