1. Draw Scatter Plots and Best-Fitting Lines
Notes 2.6
Draw Scatter Plots and Best-Fitting Lines

2. Scatter Plot
A graph of a set of data pairs (x, y).

3. Correlations: Positive Correlation:
y tends to increase as x increases (positively sloped)
Negative Correlation:
y tends to decrease as x increases (negatively sloped)
Approximately no correlation:
The points show no obvious pattern

4. Describe the correlation:

5. Describe the correlation:

6. Approximating a Best-Fitting Line:
Step 1: Draw a scatter plot of the data
Step 2: Sketch a line that follows the trend most closely (there should be about as many points above the line as below)
Step 3: Choose two points on your sketch (they do not have to be actual data points)
Step 4: Write the equation of the sketched line

7. Example: Approximate a best-fitting line:1 2 3 4 5 6 7 y
280
295
322
395
425
471
511
548
Use your line to predict y when x is 10.
Write the equation of your line.
Calculate y when x = 10.

8. Homework:
Page , 10-16