Define a linear model that could be used to assess the claim that "As single factors, neither having published papers nor having taken a biostatistics class predicts the duration of time to earn a PhD; however, together, these two factors have a negative association with time to PhD." Note this is a negative association with time; lower time to PhD is generally a good thing!

• Explicitly label parameters and variables.
• For each parameter, say whether you expect it to be negative/zero/positive if the claim were true.
• Finally, assuming your data were to support the claim, describe a method by which you could formally assess whether the result you get is likely spurious or likely a true association. Your description should be detailed enough that someone could actually implement it.