Linear regression is used to predict the value of one variable from another variable. Since it is based on correlation, it cannot provide causation. In addition, the strength of the relationship between the two variables affects the ability to predict one variable from the other variable; that is, the stronger the relationship between the two variables, the better the ability to do prediction.

For example, given this data on literacy and undernourishment, we can create a scatter plot which shows that there seems to be a relationship between the variables.

LITERACY AND HUNGER Percentage Who Are Literacy and Undernourishment Literale Undernourished Country 50 y = -0.5539x + 55.621 Cuba 100 45 R? = 0.8341 Egypt 71 40 Ethiopia 36 35 Grenada 95 7 30 Italy 25 Jamaica 20 Jordan 91 Pakistan 50 24 15 Russia 3 10 Togo 53 24 5 Uganda 67 19 O Source: The Penguin State of the World Arin 308 20 40 60 80 100 120