Lab Manual - eScience Labs

Lab 1 : Scienfic Method
Controlled Variable: This variable, or variables (there could be many) reflect the factors
that could influence the results of the experiment, but are not the planned changes the
scienst is expecng (by changing the independent variable). These variables must be
controlled so that the results can be associated with some change in the independent
variable.
When designing the experiment, establish a clear and concise procedure. Controls must be idenfied to
eliminate compounding changes that can influence the results. Oen mes, the hardest part of designing
an experiment is not figuring out how to test the one factor you focus on, but in trying to eliminate
the oen hidden influences that can skew results. Taking notes when conducng an experiment is important,
whether it is recording the temperature, humidity, me of day, or another environmental condion
that may have an impact on the results. Also remember that replicaon is fundamental to scien-
fic experiments. Before drawing conclusions, make sure your data is repeatable. In other words, make
sure the experiment provides significant results over mulple trials.
Oen, the best way to organize data for analysis is as a table or a graph. Remember, any table or graph
should be able to stand on its own. In other words, another scienst should be able to pick up the table
or graph and have all of the informaon necessary to interpret it, with no other informaon.
Table: A well-organized summary of data collected. Only include informaon relevant to the hypothesis
(e.g. don’t include the color of the plant because it’s not relevant to what is being tested). Always
include a clearly stated tle, label your columns and rows and include the units of measurement.
For our example:
Table 1: Plant Growth With and Without Added Nutrients
Variable Height Wk1 (mm) Height Wk. 2 (mm) Height Wk. 3 (mm) Height Wk. 4 (mm)
Control
(without nutrients)
Independent
(with nutrients)
3.4 3.6 3.7
3.5 3.7 4.1 4.6
4.0
Graph: A visual representaon of the relaonship between the independent and dependent variable.
Graphs are useful in idenfying trends and illustrang findings. Rules to remember:
• The independent variable is always graphed on the x-axis (horizontal), with the dependent
variable on the y axis (vercal).
• Use appropriate numerical spacing when plong the graph, with the lower numbers
starng on both the lower and le hand corners.
• Always use uniform or logarithmic intervals. For example, if you begin by numbering, 0,
10, 20, do not jump to 25 then to 32.
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