• Describe the connection between the residual and the position of a data point relative to the line of best fit.
• Create and use a residual plot to identify influential points and determine the most appropriate regression model.
• Determine the reliability of predictions from the line of best fit using the residuals and standard error of the residuals.

Model Adequacy and Residuals

Food insecurity

In 2021, it was reported that [latex]10.2\%[/latex] of households were food insecure at least some time during the year. ^[1] “Food insecure” means that their access to adequate food for active, healthy living is limited by lack of money and other resources. Additionally, [latex]32.1\%[/latex] of households with incomes below the Federal poverty line were food insecure. Rates of food insecurity were substantially higher than the national average for single-parent households and for Black and Hispanic households.

Feeding America stated: “Healthy bodies and minds require nutritious meals at every age. But when people don’t have enough food or have to choose inexpensive foods with low nutritional value, it can seriously impact their health. For example, for food-insecure adults living with diabetes, the choice between food and controlling the disease can even lead to complications like kidney disease, eye disease, and nerve damage. Family members in food-insecure households are also more likely to struggle with psychological and behavioral health issues. And kids struggling to get enough to eat are more likely to have problems in school and other social situations.”^[2]

Select the data set Organic Foods in the statistical tool below.

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The data set Organic Foods^[3] consists of the number of organic foods offered at [latex]37[/latex] grocery stores in San Antonio, Texas, in 2019. The number of organic foods offered at each store is plotted against the average income of the ZIP code in which each store is located. All stores are from the same grocery company.

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