1. Data Analysis and Statistics

2. Scatterplots
A Scatter (XY) Plot has points that show the relationship between two sets of data.

3. Ice Cream Sales vs Temperature
Example
The local ice cream shop keeps track of how much ice cream they sell versus the noon temperature on that day. Here are their figures for the last 12 days:
Ice Cream Sales vs Temperature
Temperature °C
Ice Cream Sales
14.2°
$215
16.4°
$325
11.9°
$185
15.2°
$332
18.5°
$406
22.1°
$522
19.4°
$412
25.1°
$614
23.4°
$544
18.1°
$421
22.6°
$445
17.2°
$408

4. Types of Relationships
Scatter plots often show a pattern, trend, or relationship between the variables.

6. Lines of Best Fit
A line on a scatter plot showing the general direction that a group of points seem to be heading.

7. Finding an equation of a line of best fit.
The line is linear---therefore it should be in the form of y = mx + b.
Recall, m is the slope (rise/run)
Recall, b is the y intercept (when x = 0), AKA the starting point. 2 2

8. Finding an equation of a line of best fit.
We need to pick two points on our line.
(11, 150)
(20, 450)
Now, calculate the slope using the formula---everyone try!.
M = 33.3
So, we have: y = 33.3x + b

9. Finding an equation of a line of best fit.
So, we have: y = 33.3x + b y x
We can use the point (11, 150) to solve for b!
Our Equation:
y = 33.3x – 216.3
SOLVE: 150 = 33.3 (11) + b
So, b =

10. Steps Draw a best fit line Choose 2 points Calculate the slope
Use one of the points and the slope to find b.
Write your equation

12. Selecting Statistical Displays
Mr. G’s class charted high temperatures for various cities. The graphs show four ways to display the data.

13. Each display has it’s pros…