Ch. 2 Sect. 3
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Transcript Ch. 2 Sect. 3
Ch. 2 Sect. 3
VISUALIZING DATA
Graphing Data
Charts are used to help analyze data
Independent variable
Variable that is changed or manipulated
Experimenter can control directly
Dependant variable
Outcome of dependant “depends” on the independent variable
Graphing Circular objects
Use a meterstick to measure the diameter of four
circular objects and a string to measure
circumference
Object
Diameter
Circumference
Graphing Data
Use the data and make a circumference vs. diameter
graph
X-axis = Diameter
Y-axis = circumference
The graph shows a linear relationship
Slope should be about 3.14
Expressed as circumference = 3.14 x diameter
Formula
Equals Pi (л)
Linear Relationships
Straight line through all data points
Dependant varies linearly with Independent
Y = mx + b
Slope (m) is the ratio of vertical change to the
horizontal change
Find by selecting 2 points far apart
Should not be data points but points on the line
m = Δy (rise) / Δx (run)
Linear Relationships
Y – Intercept (b) is the point at which the line
crosses the y-axis when the value of x is zero
When y-intercept is zero, b = 0, equation is y = mx
Non-linear Relationships
When graphs being presented are not in a straight
line
Graphed in a curved line or Parabola
Related by the Quadratic Relationship
y = ax2 + bx + c
One variable depends on the square on another
Non-linear Relationships
Non-linear Relationships
Inverse repationships
Hyperbola
One variable is dependant on the inverse of another
y = (a / x) or xy = a
a is constant