GRAPHING DATA

GRAPHING

·        Graphs are a useful tool in science.

·        The visual characteristics of a graph make trends in data easy to see.

·        One of the most valuable uses for graphs is to "predict" data that is not measured on the graph

Graphing steps:

—  Identify the Variables

—  Determine the range

—  Determine the scale

—  Number and label each axis

—  Plot the points

—  Draw the graph

—  Give your graph a title

IDENTIFY THE VARIABLES:

—  Independent Variable -
(the thing you changed)

·        Goes on the X axis (horizontal)

·        Should be on the left side of a data table.

—  Dependent Variable -
(changes with the independent variable)

·        Goes on the Y axis (vertical)

·        Should be on the right side of a data table.

RANGE

—  Subtract the lowest data value from the highest data value.

—  Do each variable separately.

SCALE

—  Determine a scale,
(the numerical value for each square),
that best fits the range of each variable.

—  Spread the graph to use MOST of the available space.

LABEL THE AXIS’s

—  You need to tell everyone reading your graph what the graph means.

—  Be sure to include units.

PLOTTING

—  Plot each data value on the graph with a dot. You can put the data number by the dot, if it does not clutter your graph.

DRAWING

—  Draw a curve or a line that best fits the data points.

—  Most graphs of experimental data are not drawn as "connect-the-dots".

THE TITLE

—  Your title should clearly tell what the graph is about.

—   If your graph has more than one set of data, provide a "key" to identify the different lines

—  While your high school teachers might not like it, I do like putting your name in the title of the graph.

—  Joy’s Age and Weight …hehehe

INTERPOLATION

—  Interpolate: predicting data between two measured points on the graph.

EXTRAPOLATION

Extrapolate: extending the graph, along the same slope, above or below measured data

—  A very clear and very precise explanation of the items being measured.

—   A method to ensure that anyone making the measurement will get the same answer.

—  Basically you are deciding how each variable is being measured.

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—  In other words it will depend on what you are trying to measure and you have to ask or use your common sense on how to do  it.