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
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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
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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
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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
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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
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One variable is dependant on the inverse of another
y = (a / x) or xy = a
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a is constant