Even very young children perform rudimentary experiments to learn about case studies in clinical laboratory science pdf world and how things work. Experiments vary greatly in goal and scale, but always rely on repeatable procedure and logical analysis of the results.
A child may carry out basic experiments to understand gravity, while teams of scientists may take years of systematic investigation to advance their understanding of a phenomenon. Experiments and other types of hands-on activities are very important to student learning in the science classroom. Experiments can raise test scores and help a student become more engaged and interested in the material they are learning, especially when used over time. In such an experiment, if all controls work as expected, it is possible to conclude that the experiment works as intended, and that results are due to the effect of the tested variable. However, an experiment may also aim to answer a “what-if” question, without a specific expectation about what the experiment reveals, or to confirm prior results. If an experiment is carefully conducted, the results usually either support or disprove the hypothesis.
17th century, became an early and influential supporter of experimental science. Having first determined the question according to his will, man then resorts to experience, and bending her to conformity with his placets, leads her about like a captive in a procession. Bacon wanted a method that relied on repeatable observations, or experiments. Notably, he first ordered the scientific method as we understand it today. In the centuries that followed, people who applied the scientific method in different areas made important advances and discoveries. Experiments might be categorized according to a number of dimensions, depending upon professional norms and standards in different fields of study. A good example would be a drug trial.
Most often, tests are done in duplicate or triplicate. A positive control is a procedure similar to the actual experimental test but is known from previous experience to give a positive result. A negative control is known to give a negative result. The positive control confirms that the basic conditions of the experiment were able to produce a positive result, even if none of the actual experimental samples produce a positive result. The negative control demonstrates the base-line result obtained when a test does not produce a measurable positive result. Most often the value of the negative control is treated as a “background” value to subtract from the test sample results.
The teaching lab would be equipped with a protein standard solution with a known protein concentration. Students could make several positive control samples containing various dilutions of the protein standard. Negative control samples would contain all of the reagents for the protein assay but no protein. In this example, all samples are performed in duplicate.
Controlled experiments can be performed when it is difficult to exactly control all the conditions in an experiment. This ensures that any effects on the volunteer are due to the treatment itself and are not a response to the knowledge that he is being treated. For example, an experiment on baking bread could estimate the difference in the responses associated with quantitative variables, such as the ratio of water to flour, and with qualitative variables, such as strains of yeast. These hypotheses suggest reasons to explain a phenomenon, or predict the results of an action. An example might be the hypothesis that “if I release this ball, it will fall to the floor”: this suggestion can then be tested by carrying out the experiment of letting go of the ball, and observing the results. The null hypothesis is that there is no explanation or predictive power of the phenomenon through the reasoning that is being investigated.
Once hypotheses are defined, an experiment can be carried out and the results analysed to confirm, refute, or define the accuracy of the hypotheses. The term “experiment” usually implies a controlled experiment, but sometimes controlled experiments are prohibitively difficult or impossible. To the degree possible, they attempt to collect data for the system in such a way that contribution from all variables can be determined, and where the effects of variation in certain variables remain approximately constant so that the effects of other variables can be discerned. Usually, however, there is some correlation between these variables, which reduces the reliability of natural experiments relative to what could be concluded if a controlled experiment were performed. Also, because natural experiments usually take place in uncontrolled environments, variables from undetected sources are neither measured nor held constant, and these may produce illusory correlations in variables under study. For example, in astronomy it is clearly impossible, when testing the hypothesis “Stars are collapsed clouds of hydrogen”, to start out with a giant cloud of hydrogen, and then perform the experiment of waiting a few billion years for it to form a star.