Experimental Design -Pre Lab Flowchart
; Be able to define the key elements given below for an experimental design.
; Be able to construct a pre lab flowchart for a given experiment (hint..hint ?)
Scientific Investigation: A multifaceted and organized scientific study of the natural world that involves making observations; asking questions; gathering information through planned study in the field, laboratory, or research setting; and using tools to gather data that is analyzed to find patterns and is subsequently communicated.
Purpose or question: identify the question(s) that is to be answered by this scientific investigation or the purpose of the scientific investigation.
Hypothesis: a tentative, explanation for what you observe. This explanation must be testable. This usually takes the form of an “if, and, then” format that indicates a causal or correlational relationship between variables. The manipulated variable is stated in the “if” statement and represents the possible
causal agent. The effect is stated in the “then” phrase and is the responding or measured variable of the
Experimental design: how you will go about testing your hypothesis. Most often, the main purpose of your design is to test the effect of the manipulated variable on the responding variable.
Variable: Any changed or changing factor used to test a hypothesis or prediction in an investigation that could affect the result.
Responding (dependent) variable: the variable you are measuring (what you count or record in your
Manipulated (changed/independent) variable: the variable that you vary (manipulate) during the
experiment. It is the variable that you think will affect the responding (dependent) variable.
Treatments: appropriate levels (values) that you assign to the independent variable.
Control: a treatment where the manipulated variable is held at an established level or eliminated. The control or controlled treatment serves as a standard that allows the investigator to decide whether the predicted effect is really due to the manipulated variable.
Controlled variable(s): all manipulated variables other than the one being studied that are to be held constant. Not to be confused with the control (controlled treatment).
Procedure (method): the stepwise method, or sequence of steps, to be performed in the experiment. It should be recorded in a laboratory notebook before initiating the experiment, and any exception or modification should be noted during the experiment. The procedures may be designed from research published in scientific journals, through collaboration with colleagues in the lab, or by the means of one’s own novel and creative ideas. The process of outlining the procedure includes determining control treatments, levels of treatments and number of replications.
Trials: Repetitions of data collection protocols in an investigation. Synonym: replicates.
Prediction: the expected outcome of your experiment. In other words, this is your “educated guess”.
Your prediction must be based on your hypothesis to be valid. Synonym: Making an extrapolation.
experiment Experimental Design Flowchart multiple
times P(trials or Purpose or Question rreplicates)
… Experimental design and…(between dashed lines) ….
fResponding Variable Manipulated Variable ControllED Variable(s) “dependent variable” “changed or independent variable” l(constant across treatments) (what you are measuring) X axis (identify at least 3) Y axis o
Procedure Treatments c“methods” levels? control?
Predicted Result of Experiment rthen.. Form, then wait and see (oh.. the suspense!
Observed Result of Experiment