predict()

The predict() function will generate the prediction(s) from a model. 

Example 1:

# Calculate the predictions from the Sex model of Thumb

# Use the lm() function to specify the model

predict(lm(Thumb ~ Sex, data = Fingers))

# Alt: Save the model into an object first

# then specify the name of the object as the argument

# (this method will produce the same output as the method above)

sex_model <- lm(Thumb ~ Sex, data = Fingers)

predict(sex_model) 

Example output (truncated):

Example 2:

To see each prediction in context, you might consider saving the predictions into the data frame as a new column to see more closely what the predict() function is doing.

# Save the predictions back into the data frame

sex_model <- lm(Thumb ~ Sex, data = Fingers)​

Fingers$Thumb_predict <- predict(sex_model)

# Select a few rows and the relevant columns to compare

head(select(Fingers, Thumb, Sex, Thumb_predict))

Example output:

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