title: multivariable regression with ggplot2
body: <p>I need to create a multivariable regression line using ggplot. </p>
  
  <p>My data:</p>
  
  <pre><code>dput(head(x2,15))
  structure(list(Date = structure(c(15608, 15609, 15610, 15611, 
  15612, 15613, 15614, 15615, 15616, 15617, 15618, 15619, 15620, 
  15621, 15622), class = "Date"), Cpu = c(77.0763, 51.8909, 59.3229, 
  89.5822, 87.7448, 80.4413, 57.5009, 99.8185, 99.9969, 91.5528, 
  50.0793, 56.4049, 57.808, 51.0453, 56.0505), Memory = c(369.667979452055, 
  341.572253381722, 345.013066490241, 334.520135424091, 374.107056613899, 
  1592.38342810723, 470.204599904169, 393.802909594735, 540.817571059432, 
  425.49563812601, 438.326775174387, 614.417456359102, 1255.63550519358, 
  466.993243243243, 358.445879354291), Response = c(52.25, 48.36, 
  49.23, 50.99, 48.63, 46.11, 43.03, 45.35, 50.03, 46.18, 47.39, 
  43.28, 55.36, 50.59, 50.44)), .Names = c("Date", "Cpu", "Memory", 
  "Response"), row.names = c(1L, 4L, 6L, 7L, 9L, 10L, 13L, 16L, 
  19L, 25L, 29L, 32L, 35L, 39L, 42L), class = "data.frame")
  </code></pre>
  
  <p>I can do this between <code>Response</code> and <code>Cpu</code>:</p>
  
  <pre><code>ggplot(x2, aes(Response)) + 
     geom_point(aes(y = Memory), size = 2, colour = "blue") +
     geom_point(aes(y = Cpu), size = 2, colour = "orange") + 
     geom_smooth(method = "lm", formula = "Response ~ CPU+Memory", 
                 size = 1.5, colour = "red", se = T)
  </code></pre>
  
  <p>I am getting this error:</p>
  
  <pre><code>Error: stat_smooth requires the following missing aesthetics: y
  </code></pre>
  
  <p>Any ideas?</p>