Scientists use the scientific method to ask and answer questions about the world by doing experiments and making observations. The steps of the scientific method are: ask and research a question, develop a hypothesis, carry out an experiment to test the hypothesis, analyze the data, make conclusions and present the results. The scientific method enables scientists to look for cause-and-effect relationships so they are able to determine the answer to questions such as which baby lotions make the skin softer.
Every scientific experiment starts with a question, one that often comes from observing the world. The question should be clear and focused. For example, determine before beginning your work precisely what attributes must be in existence for a baby lotion to be effective. Does it mean that the lotion makes the skin soft or that it also heals cracked skin? Is the lotion effective on all skin types, or just on infants' skin? Research the question to see if others have already determined the answer. While conducting this research, you may also find examples of similar experiments that will help you design your own.
A hypothesis is an educated guess about what will happen in an experiment and it's written using both independent and dependent variables. The independent variable is the thing you change in the experiment -- such as the brand of lotion -- and the dependent variable is the thing that you measure -- such as skin softness. The hypothesis in this example might be: If lotion is applied to the skin every day for a week, the skin will be softer with 50 percent fewer cracks. The hypothesis should be written so it can be easily tested by conducting an experiment.
Testing skin lotion is similar to clinical trials used to see if new drugs or treatments work. Consider using a double-blind method in which the identify of the lotion is hidden until the conclusion of the experiment. Use small containers marked with a special code that corresponds to the brand of lotion. Give the lotions to the people testing them in a random fashion. The specific random order may be decided by utilizing such methods as rolling dice; this is called randomization. Compare the lotions to a control -- a person who does not use any lotion or even a tester's opposite arm.
Before conducting the experiment, decide which data to collect about the lotion, such as softness of the skin, ability to heal cracked skin, greasiness and cost per ounce. The last two are not related directly to product effectiveness but they could certainly help determine whether people will use a particular lotion. Make sure to run each part of the experiment several times to make sure the first results are maintained throughout. Present the results using tables and graphs, as well as written descriptions of the experiment, you hypothesis and your conclusions.