Linear Correlations

Describe the correlation in the graph shown.

• Strong Negative
• Strong Positive
• Weak Negative
• Weak Positive

Describe the correlation in the graph shown.

• Strong Negative
• Strong Positive
• Weak Negative
• Weak Positive

Describe the correlation in the graph shown.

• No Correlation
• Strong Negative
• Weak Positive
• Weak Negative

A correlation shows that two things are

• related
• causing each other
• unrelated
• causation

Which is a NOT condition not needed for correlation

• Quantitative Variables
• Straight Enough
• Large Enough Sample
• Outliers?

Some data were collected on the weight of a male while laboratory rat for the first 25 weeks after its birth. The linear regression equation is weight^=100 + 40(time). Which is the best description of the slope for this regression equation in context of the problem?

• The slope of the line of regression is the time since birth of the rate. It demonstrates the predicted weight of a laboratory rate after so many months since birth.
• The slope is 40 grams/week which means the mouse gains about 40 grams per week after birth.
• The slope is 40 and it means for every increase in weeks the graph will increase. 
• The slope is 40, which tells us the line increases. 

Which is the best description of the y - intercept for the linear regression equation of the rats: weight^ = 100 + 40(time)?

• The y-intercept is 100 which means the rat is predicted to weigh 100 grams at birth. 
• The y-intercept is 100, which is where the graph crosses the y-axis. 
• 100 is where the data starts on the y-axis. 

Write the linear regression equation for the data set foot length (x) and height (y).

• y = 117.99 + 1.878x
• height^ = 28.39(foot length) + 1.155
• y = 1.878 + 117.99x
• height^ = 117.99 + 1.878(foot length)

What is the correlation value?

• .209
• .457
• .13
• .361

The points in the scatterplot represent paired observations (x, y) where x is an individual’s weight and y is the time (in seconds) it takes for walking on a treadmill to raise the individual’s pulse rate to 140 beats per minute.  The open circles correspond to females and the dark squares to males. 

• There is a positive correlation r between gender and weight, since men tend to weigh more than women. 
• There is a negative correlation r between weight and time for both males and females. 
• In general, males tend to take less time to have their pulse rate raised to 140 bpm while walking on the treadmill.