Regression Lines and Correlation

Is this a positive, negative, or no relationship?

• positive relationship

• negative relationship

• no relationship

Is this a positive, negative, or no relationship?

• positive relationship

• negative relationship

• no relationship

Is this a positive, negative, or no relatioship?

• Positive relationship

• Negative relationship

• No relationship

Is r = -0.87 strong, moderate, or weak?

• strong

• moderate

• weak

A positive relationship (correlation coefficient) means...

• variables have the same behavior (both up or both down)

• variables have opposite behavior (one up, one down)

• the variables are happy :)

• the variables are sad :(

What is the linear regression formula?

• y=mx+b

• y=ax+b

• y=a+bx

Use your calculator to compute the least-squares regression line for the following data:

x: 3.9, 5.8, 4.8, 3.3, 1.8, 3.4, 3.2

y: 4.6, 4.1, 5.2, 4.5, 9.2, 5.6, 4.3

• y = -0.97x+8.99

• y = 0.97x-8.99

• y = -62x+6443

• = 62x-6443

If x is temperature and y is coffee sales, use the following formula to determine the coffee sales on a 34° day.

y = -60x+6443

• $4584

• $4673

• $8303

How do you find the residual?

• predicted value - actual value

• actual value - predicted value

• what values are you talking about?

Data was collected on the weight of a male  laboratory rat for the first 25 weeks after its birth. The linear regression equation is 
y= 40x+100, where x is number of weeks and y is weight in grams. 
What does the y-intercept mean in context of the problem?

• The predicted weight of the rat in year 0. 
• The predicted weight of the rat at birth. 
• The current weight of the rat. 
• The average increase in the rat's weight.