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EXPERIMENTAL & CONTROL GROUPS

#1-7: WHAT ARE THE EXPERIMENTAL AND CONTROL GROUPS OF AN EXPERIMENT?

LESSON #1-7:
WHAT ARE THE EXPERIMENTAL AND CONTROL GROUPS OF AN EXPERIMENT?

1) MOST EXPERIMENTS HAVE TWO GROUPS CREATED BY THE PROCEDURE: THE EXPERIMENTAL GROUP AND THE CONTROL GROUP.

2) THE EXPERIMENTAL GROUP (ALSO CALLED THE VARIABLE GROUP) IS THE GROUP IN THE EXPERIMENT THAT GETS THE INDEPENDENT VARIABLE. THE INDEPENDENT VARIABLE (THE "GOODIE") IS WHAT THE SCIENTIST IS INTERESTED IN AND IS STUDYING. THE SCIENTIST WANTS ONLY THIS VARIABLE TO AFFECT OR TO CAUSE THE RESULTS (THE DEPENDENT VARIABLE) OF THE EXPERIMENT.

3) THE CONTROL GROUP IS THE GROUP IN THE EXPERIMENT THAT DOES NOT GET THE INDEPENDENT VARIABLE (NO GOODIE FOR YOU!). THE CONTROL GROUP WILL BE USED AS A COMPARISON IN ORDER TO FIGURE OUT WHAT KINF OF EFFECT THE INDEPENDENT VARIABLE HAD ON THE RESULTS.

EXAMPLE: WHAT IS THE EFFECT OF LIGHT ON PLANT GROWTH?
THIS EXPERIMENT HAS BOTH GROUPS IN IT. THE EXPERIMENTAL GROUP WILL GET THE INDEPENDENT VARIABLE OF LIGHT, BUT THE CONTROL GROUP WILL GET NO LIGHT. THE RESULTS OF EACH GROUP WILL BE COMPARED TO FIND OUT IF THE PLANTS GROW BETTER IN LIGHT OR NO LIGHT.

4) SOME EXPERIMENTS ONLY HAVE 1 GROUP: THE EXPERIMENTAL GROUP BECAUSE THEY ARE ONLY CONCERNED WITH DIFFERENT VARIETIES OF THE INDEPENDENT VARIABLE. NO CONTROL GROUP IS NEEDED FOR THE EXPERIMENT.

EXAMPLE: WHAT IS THE EFFECT OF DIFFERENT TEMPERATURES ON PLANT GROWTH?

IN THIS EXPERIMENT THERE IS NO CONTROL GROUP BECAUSE YOU CANNOT PUT PLANTS IN AN ENVIRONMENT THAT HAS NO TEMPERATURE. INSTEAD YOU HAVE AN EXPERIMENT THAT DEALS WITH VARYING OR DIFFERENT TEMPERATURES, LIKE COLD, WARM, AND HOT. yOU ARE TRYING TO FIGURE OUT WHICH TEMPERATURE IS BEST FOR THE PLANTS TO GROW IN. THIS EXPERIMENT ONLY HAS AN EXPERIMENTAL GROUP.
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