{"id":4260,"date":"2019-06-17T18:25:33","date_gmt":"2019-06-17T18:25:33","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/1-4-scientific-investigations\/"},"modified":"2023-11-30T17:46:09","modified_gmt":"2023-11-30T17:46:09","slug":"1-4-scientific-investigations","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/1-4-scientific-investigations\/","title":{"raw":"1.4\u00a0Scientific Investigations","rendered":"1.4\u00a0Scientific Investigations"},"content":{"raw":"
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\"Doing\" Science<\/h1>\r\n<\/div>\r\nScience is as much about doing\u00a0as\u00a0knowing. Scientists are always trying to learn more and gain a better understanding of the natural world. There are basic methods of gaining knowledge that are common to all of science. At the\u00a0heart\u00a0of science is the scientific investigation. A\u00a0[pb_glossary id=\"5647\"]scientific investigation[\/pb_glossary]<\/strong>\u00a0is a systematic approach to answering questions about the physical and natural world.\u00a0Scientific investigations can be observational\u00a0\u2014\u00a0 for example, observing a cell under a\u00a0microscope\u00a0and recording detailed descriptions. Other scientific investigations\u00a0are\u00a0experimental \u2014 for example, treating a cell with a drug while recording changes in the behavior of the cell.\r\n\r\nThe flow chart below\u00a0shows the typical steps followed in an experimental\u00a0scientific investigation.\u00a0The series of steps shown in the flow chart is frequently referred to as the\u00a0[pb_glossary id=\"5645\"]scientific method[\/pb_glossary].<\/strong>\u00a0Science textbooks often present this simple, linear \"recipe\" for a scientific investigation. This is an oversimplification of how science is actually done, but it\u00a0does highlight the basic plan and purpose of\u00a0an experimental\u00a0scientific investigation: testing ideas with evidence. Each of the steps in the flow chart is discussed in greater detail below.\r\n\r\n[caption id=\"attachment_45\" align=\"alignleft\" width=\"300\"]\"Diagram Figure 1.4.1 The Scientific Method is a never ending cycle.<\/em>[\/caption][pb_glossary id=\"5809\"]Science[\/pb_glossary]<\/strong> is actually a complex endeavor that cannot be reduced to a single, linear sequence of steps, like the instructions on a package of cake mix. Real science is nonlinear, iterative (repetitive), creative, unpredictable, and exciting. Scientists often undertake the steps of an investigation in a different sequence, or they repeat the same steps many times as they gain more information and develop new ideas. Scientific investigations often raise new questions as old ones are answered. Successive investigations may address the same questions, but at ever deeper levels. Alternatively, an investigation might lead to an unexpected\u00a0observation that sparks a new question and takes the\u00a0research\u00a0in a completely different direction.\r\n\r\nKnowing how scientists \"do\" science can help you in your everyday life, even if you aren't a scientist. Some steps of the scientific process\u00a0\u2014\u00a0such as asking questions and evaluating evidence\u00a0\u2014\u00a0can be applied to answering real-life questions and solving practical problems.\r\n
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Making Observations<\/h1>\r\n<\/div>\r\n\r\n[caption id=\"attachment_46\" align=\"alignright\" width=\"300\"]\"A Figure 1.4.2 Health professionals use many tools in order to make observations.<\/em>[\/caption]\r\n\r\nTesting an idea typically begins with observations. An\u00a0[pb_glossary id=\"5649\"]observation[\/pb_glossary]<\/strong> is anything that is detected through human senses or with instruments or measuring devices that enhance human senses. We usually think of observations as things we see with our eyes, but we can also make observations with our sense of touch, smell, taste, or hearing. In addition, we can extend and improve our own senses with instruments such as thermometers and microscopes. Other instruments can be used to sense things that human senses cannot detect at all, such as ultraviolet light or radio waves.\r\n\r\n[caption id=\"attachment_47\" align=\"alignleft\" width=\"300\"]\"A Figure 1.4.3 Alexander Fleming examining bacterial growth.<\/em>[\/caption]Sometimes, chance observations lead to important scientific discoveries. One such\u00a0observation\u00a0was made by the Scottish biologist Alexander Fleming<\/a> (pictured\u00a0below) in the 1920s. Fleming's name may sound familiar to you because he is famous for\u00a0a\u00a0major\u00a0discovery. Fleming had been growing a certain type of\u00a0bacteria\u00a0on glass plates in his lab when he noticed that one of the plates\u00a0was\u00a0contaminated with\u00a0mold. On closer examination, Fleming observed that the area around the mold was free of\u00a0bacteria.\r\n

Asking Questions<\/h1>\r\nObservations often lead to interesting questions. This is especially true if the observer is thinking like a scientist. Having scientific training and knowledge is also useful. Relevant background knowledge and logical thinking help make sense of observations so the observer can form particularly salient questions. Fleming, for example, wondered whether the\u00a0mold\u00a0\u2014\u00a0or some substance it produced\u00a0\u2014\u00a0had killed\u00a0bacteria\u00a0on the plate. Fortunately for us, Fleming didn't just throw out the mold-contaminated plate. Instead, he investigated his question and in so doing, discovered the antibiotic penicillin.\r\n
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Hypothesis\u00a0Formation<\/h1>\r\n<\/div>\r\nTypically, the next step in a scientific investigation is to form a\u00a0hypothesis. A\u00a0[pb_glossary id=\"5579\"]hypothesis[\/pb_glossary]<\/strong>\u00a0is a possible answer to a scientific question. But it isn\u2019t just\u00a0any<\/em>\u00a0answer. A hypothesis must be based on scientific knowledge. In other words, it shouldn't be at odds with what is already known about the natural world. A hypothesis also must be logical, and it is beneficial if the hypothesis is relatively simple. In addition, to be useful in science, a hypothesis must be testable and [pb_glossary id=\"5376\"]falsifiable<\/strong>[\/pb_glossary]. In other words, it must be possible to subject the hypothesis to a test that generates evidence for or against it. It must also be possible to make observations that would disprove the hypothesis if it really is false.\r\n\r\nFor example,\u00a0Fleming's hypothesis might have been:\u00a0\u201cA particular kind of bacteria growing on a plate will die when exposed to a particular kind of\u00a0mold.\u201d\u00a0The hypothesis is logical and based directly on observations. The hypothesis is also simple,\u00a0involving just one type each of mold and bacteria growing on a plate. In addition, hypotheses are subject to \"if\/then\" conditions.\u00a0Thus, Fleming might have stated, \"If a certain type of mold is introduced to a particular kind of bacteria growing on a plate, then the bacteria will die.\" This makes\u00a0the hypothesis\u00a0easy to test and ensures that it is falsifiable. If the bacteria were to grow in the presence of the mold, it would disprove the hypothesis (assuming the hypothesis is really false).\r\n
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Hypothesis Testing<\/h1>\r\n<\/div>\r\nHypothesis testing is at the\u00a0heart\u00a0of\u00a0the scientific method. How would Fleming test his hypothesis? He would gather relevant data as evidence.\u00a0[pb_glossary id=\"5581\"]Evidence[\/pb_glossary]<\/strong>\u00a0is any type of data that may be used to test a hypothesis.\u00a0[pb_glossary id=\"5583\"]Data[\/pb_glossary]<\/strong>\u00a0(singular, datum)\u00a0are essentially just observations. The observations may be measurements in an\u00a0experiment\u00a0or just something the researcher notices. Testing a hypothesis then involves using the data to answer two basic questions:\r\n
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  1. If my hypothesis is true, what would I expect to observe?<\/li>\r\n \t
  2. Does what I actually observe match what I expected to observe?<\/li>\r\n<\/ol>\r\nA hypothesis is supported if the actual observations (data) match the expected observations. A hypothesis is refuted if the actual observations differ from the expected observations.\r\n\r\nThe scientific method is employed by scientists around the world, but it is not always conducted in the order above. Sometimes,\u00a0hypothesis\u00a0are formulated before observations are collected; sometimes observations are made before hypothesis are created. Regardless, it is important that scientists record their procedures carefully, allowing others to reproduce and verify the experimental data and results. After many experiments provide results supporting a hypothesis, the hypothesis becomes a\u00a0[pb_glossary id=\"5585\"]theory[\/pb_glossary]<\/strong>.\u00a0Theories\u00a0remain theories forever, and are constantly being retested with every\u00a0experiment\u00a0and\u00a0observation. Theories can never become fact or\u00a0[pb_glossary id=\"5587\"]law[\/pb_glossary]<\/strong>.\r\n\r\nIn science, a law is a mathematical relationship that exists between observations under a given set of conditions. There is a fundamental difference between observations of the physical world and explanations of the nature of the physical world. Hypotheses and\u00a0theories\u00a0are explanations, whereas laws and measurements are observational\r\n
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    1.4 Summary<\/span><\/h1>\r\n<\/header>\r\n
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