Fitted Lines (Graphing)

Using the eth_allrounds_final data, add a fitted line and confidence interval to a scatter plot, and adjust the appearance.

1. Make a scatter plot with yield (yield_kg) on the y-axis and inorganic fertilizer (inorganic_fertilizer_value_USD) on the x-axis, restricting observations to only maize (crop == 3).
   • Add a fitted line with a confidence band using lfitci in a twoway graph.
   • Place the legend on the bottom (pos) in three columns (col).
   • Use very small, hollow circular markers for the points.
   • Change the color of the line to maroon and the pattern of the line to be solid (use lcolor and lpattern).
   • Make the color of confidence band gray and partially transparent (gray%50) so the points and line remain visible (use fcolor).
   • Label the x-axis “Inorganic Fertilizer (USD)” and the y-axis as “Maize Yield (kg)”
2. What is the relationship between yield and fertilizer use? Positive? Negative? No relationship?

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