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Math and Science. How Math is Used. Mathematics is used to describe natural objects and populations Mathematics is used to model natural systems. Measuring Systems. Measuring systems are constructed from a few minimum necessary elements Length Mass Time Temperature. Describing Objects.
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How Math is Used • Mathematics is used to describe natural objects and populations • Mathematics is used to model natural systems
Measuring Systems • Measuring systems are constructed from a few minimum necessary elements • Length • Mass • Time • Temperature
Describing Objects • Measurements can be combined to describe an object • Volume = length 3 (ex. cm3 , m 3) • Density = mass/volume (ex. g/cm3, mg/m3) • Concentration = mass/volume (ex. g/ml, mg/L)
Describing Processes • Measurements can be combined to describe a process • Velocity = length/time (ex. m/sec, km/hr)
Types of Data • Discrete Data • Each item measured is a discrete or whole unit • Continuous Data • Points along a continuum • Points along a subdivided scale
Types of Measurement Scales • Nominal and Ordinal Scales • Used to measure discrete data • Interval and Ratio Scales • Used to measure continuous data
Scales of Measurement • Nominal and Ordinal Scales • Used for discrete data • Sorting of whole units into groupings
Nominal Scale For discrete data • Whole units sorted into groupings of equal value. • No measure of difference between items • Ex. Numbers of males and females
Ordinal Scale For discrete data • Whole units sorted into groupings of relative value • Measure of difference between items in groups • Ex. Fish ranked by size small fish, medium fish, and big fish
Colorimetric Comparisons Nominal or Ordinal?
Scales of Measurement • Interval and Ratio Scales • Used for continuous data • Indicates the distance between items
Interval and Ratio Scales • The ratio between any two intervals is independent of the unit of measurement and of the zero point. • No matter which scale you use the ratio of intervals remains the same.
Ratio Scale • Has a true zero point • Ex. Length, volume, weight
Interval Scale Zero point is arbitrarily set Ex. Temperature (arbitrary zero based on temperature at which water freezes)
Concentration of Added Nitrogen Ratio or Interval?