Introduction To Experimental Design

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1020L – Introduction to Experiment Design (Spring 2021)

Every discovery in chemistry comes from experimentation; it is the bread and butter for scientists in every discipline. Thus, being adept in experimental design is a significant tool. Experimental design is all about making accurate observations in a controlled environment. Consider a biologist who is seeking to determine the effect of sunlight on four plants. She is interested in observing the response in plant growth to the manipulation of sunlight –how much or how little sunlight the plants receive.

· What is her independent variable? Define independent variable.

· What is her dependent variable? Define dependent variable.

· What is the relationship between an independent variable and a dependent variable?

· The goal of the biologist’s study is to determine the relationship between sunlight and plant growth. If fertilizer and water aren’t being investigated as to how they affect plant growth, should those factors remain constant or be variable? Why? Define a constant.

· The biologist collects her data over the course of a week. Her first plant received 1 hour of sunlight per day and grew 1.25 inches. Her second plant received 2 hours of sunlight and grew 2.50 inches. Her third received 3 hours and grew 4.25 inches. The final received 4 hours of sunlight per day and grew 5.75 inches. Using this info, organize the biologist’s experimental data into a data table (be careful to represent the numbers exactly as they are given to you and label the table and what your columns and rows represent).