Description of the Scientific Process: Running Your Experiment
Running Your Experiment
So, you have designed your experiment and gathered your materials. You are ready to begin. When you run your experiment, the most important thing to do is to be consistent. If you used Brand X potting soil for the control plants, then use Brand X potting soil for the treatments (unless the experiment was testing the quality of Brand X versus Brand Y potting soil, of course.) Apply even conditions across all of your samples as best as you can to avoid introducing experimental bias. It seems really simple, but as the experiment proceeds, it can be all too easy to get sloppy and unevenly apply some condition. Likewise, make your measurements consistent. If you use a Brand X pH probe for some of your samples, use it for the rest. Define how you will dissect each insect to measure abdomen length and do it the same way each time. Doing things unevenly will make your results highly variable and unreliable.
One way to stay consistent, especially in multi-day experiments, is to take notes. Get yourself a nice notebook dedicated to your research project. In it, write down the times of what you did, exactly what you did, how much of a chemical you used, measurements you took, funny things you observe about your samples, and so on. We don’t think we’ve ever heard of anyone putting too many things in a scientific notebook. Do not underestimate the utility of the notebook. You can later use it to spot accidental experimental bias that you introduced or recreate part of your experiment for the sake of consistency. When you are creating your posters or papers for your project, you will probably find something you wrote down in your notebook important. Finally, the notebook is an artifact and a keepsake of your project.
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Sometimes, mistakes happen that threaten to end the experiment prematurely. When that happens, step back and take a deep breath. (Go and punch a pillow and yell, too. It does help.) When you have gathered your wits and achieved a Zen-like state, consider what you can do to salvage the experiment. If you added twice as much hydrochloric acid to half of your samples, you might just redesign your experiment on the fly. You’ve been taking notes, right? You can use those to describe some of your samples as being new treatments. Just write it down and carry on. Who knows? Maybe you’ll find something interesting. If it’s early enough in the experiment, or you can afford more research, you can use much of the material from a failure, and you can certainly use the lessons so hard-won. |
During an experiment, it is often critical to label your samples. If you need to redo something or just prevent yourself from double-treating and individual, labels are really important. When you take notes, you can report exactly which individual or data point was affected by a mistake. Remember to upkeep those labels, too. Organic solvents and sunlight can erase your markings, and tape can peel off. If you are working with outdoor labels, avoid permanent markers (which aren’t so permanent in the sun) and just go with pencils. Better yet, use stamped metal labels.
And those mistakes will happen. In science, the occasional spill, drop, or contamination will occur. You just have to carry on. What do you do with the would-be data points? Most often, you remove them. Keeping them around could add bias to your results. On occasion, if enough sample is destroyed, you may have to abandon the experiment, but that’s tragic. When you designed your experiment, you should have made the sample size large enough to account for data loss, so most removals should not impact your study too much. Do not be too cavalier about this aspect of running your experiment, but take some comfort in having accounted for the possibility.
When you have completed your experiment, keep as many of the materials as you can. You might find unusual results later that are unaccounted for, and you can double check that there was not something physically wrong. Your peers may also be interested in exactly what you did. For science fairs especially, artifacts of your research can be very useful for your presentation.
Observation and Finding a Problem to Study