DOWNLOAD PDF 11.5 DEFINING TREATED AND CONTROL GROUPS

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1 Chapter 1 : Scientific Control Group Active treatment concurrent control: one group is given the treatment, the other group is given an existing therapy that is known to be effective. Historical control: only one physical group exists experimentally (the experimental group). the control group is compiled from historical data. Persons using assistive technology might not be able to fully access information in this file. For assistance, please send to: Type Accommodation and the title of the report in the subject line of . This report describes the results of that analysis, which indicated that the proportion of Mexican-Americans and blacks with stage 1 and stage 2 hypertension was greater than for whites. Some participants were excluded based on more than one criterion, yielding a final study sample of 6, participants. Hypertension treatment was identified as the use of blood pressureâ lowering medication and did not include lifestyle or dietary approaches. Hypertension awareness was determined based on whether a participant was ever told they had high blood pressure by a health-care provider. Health-care coverage was categorized into three groups: All analyses were performed using statistical software to account for sampling weights and adjust variance estimates for the complex sampling design. Because multiple NHANES cycles were combined, trends over time could not be examined, and prevalence estimates could not be age adjusted. Hypertension awareness, treatment, and control were lowest among Mexican-Americans Among those with uncontrolled hypertension, awareness and treatment was greater for blacks Blacks with stage 1 hypertension had greater awareness Among those with stage 2 hypertension, blacks had greater awareness Health-care coverage for those with uncontrolled hypertension was lowest for Mexican-Americans However, among all persons with uncontrolled hypertension who were treated, the proportion who had health-care coverage was lower for Mexican-Americans Reported by Amy L. Carla Mercado, cmercado cdc. Mexican-Americans and blacks with hypertension were significantly younger than whites. Awareness and treatment was highest among blacks. This association is consistent with previous studies 6,7 and might be a result of efforts to reduce the persistent high prevalence of hypertension among blacks. Data on the number or type of medication used by participants, including two-drug combinations, were not examined in this report. To improve treatment and achieve the Healthy People goal of blood pressure control in In this study, the proportion of persons with health-care coverage was lowest among Mexican-Americans. Lack of health-care coverage has been associated with lower rates of hypertension awareness, treatment, and control 9. This might partially explain the observed lower treatment and awareness of hypertension among Mexican-Americans in this report. The findings in this report are subject to at least five limitations. Similarly, the study could not consider other Hispanic subpopulations or Hispanics as a whole because of differences in NHANES sample design between the â and â cycles. Second, hypertension awareness and treatment as well as other covariates were self-reported and subject to recall bias. Third, hypertension treatment was based only on medication use, not accounting for participants who were using lifestyle or dietary approaches to reduce blood pressure, which might have resulted in an underestimation of proportion of adults with hypertension who received "treatment. Multiple national efforts target improvements in high blood pressure prevention, treatment, and control 3. The Million Hearts initiative, co-led by CDC and the Centers for Medicare and Medicaid Services, is focusing efforts on preventing 1 million heart attacks and strokes by, partially achieved by increasing blood pressure control for 10 million persons in the United States Heart disease and stroke statisticsâ update: Hypertension among adults in the United States, â NCHS data brief, no. Ethnic differences in hypertension incidence among middle-aged and older adults: Trends in antihypertensive medication use and blood pressure control among United States adults with hypertension: Prevalence, awareness, treatment, and predictors of control of hypertension in New York City. Circ Cardiovasc Qual Outcomes ;1: The "Million Hearts" initiativeâ preventing heart attacks and strokes. N Engl J Med ; Mexican-Americans might be of any race. What is already known on this topic? It has been previously reported that one in three U. What is added by this report? Based on data from the National Health and Nutrition Examination Survey for the period â, high blood pressure control differed for whites Among those with hypertension, the proportion with stage 2 hypertension was greater for Mexican-Americans Page 1

2 What are the implications for public health practice? Page 2

3 Chapter 2 : Experimental Design in Control Group and Experimental Group, control group definition, Control Group vs Experimental Group example, experimental group definition, Research methodology An experiment is a method of scientific investigation or test under controlled conditions that is made to demonstrate a known truth or exa. Scientific method and Experimental design In controlled experiments, the same experiment is done in at least two parallel experiments that differ in only one way, with one experiment being the "control arm" and the other being the "experimental arm". Controls eliminate alternate explanations of experimental results, especially experimental errors and experimenter bias. Many controls are specific to the type of experiment being performed, as in the molecular markers used in SDS-PAGE experiments, and may simply have the purpose of ensuring that the equipment is working properly. The selection and use of proper controls to ensure that experimental results are valid for example, absence of confounding variables can be very difficult. Control measurements may also be used for other purposes: For example, if a researcher feeds an experimental artificial sweetener to sixty laboratory rats and observes that ten of them subsequently become sick, the underlying cause could be the sweetener itself or something unrelated. Other variables, which may not be readily obvious, may interfere with the experimental design. For instance, the artificial sweetener might be mixed with a dilutant and it might be the dilutant which causes the effect. To control for the effect of the dilutant, the same test is run twice; once with the artificial sweetener in the dilutant, and another done exactly the same way, but using the dilutant alone. Now the experiment is controlled for the dilutant and the experimenter can distinguish between sweetener, dilutant and non-treatment. Controls are most often necessary where a confounding factor cannot easily be separated from the primary treatments. For example, it may be necessary to use a tractor to spread fertilizer where there is no other practicable way to spread fertilizer. The simplest solution is to have a treatment where a tractor is driven over plots without spreading fertilizer and in that way the effects of tractor traffic are controlled. The simplest types of control are negative and positive controls, and both are found in many different types of experiments. Placebo-controlled study Where there are only two possible outcomes, e. If the treatment group and the negative control both produce a positive result, it can be inferred that a confounding variable is involved in the phenomenon under study, and the positive results are not solely due to the treatment. In other examples, outcomes might be measured as lengths, times, percentages, and so forth. In the drug testing example, we could measure the percentage of patients cured. In this case, the treatment is inferred to have no effect when the treatment group and the negative control produce the same results. Some improvement is expected in the placebo group due to the placebo effect, and this result sets the baseline which the treatment must improve upon. Even if the treatment group shows improvement, it needs to be compared to the placebo group. If the groups show the same effect, then the treatment was not responsible for the improvement because the same number of patients were cured in the absence of the treatment. The treatment is only effective if the treatment group shows more improvement than the placebo group. Positive[ edit ] Positive controls are often used to assess test validity. The well-established test is the positive control, since we already know that the answer to the question whether the test works is yes. Similarly, in an enzyme assay to measure the amount of an enzyme in a set of extracts, a positive control would be an assay containing a known quantity of the purified enzyme while a negative control would contain no enzyme. The positive control should give a large amount of enzyme activity, while the negative control should give very low to no activity. If the positive control does not produce the expected result, there may be something wrong with the experimental procedure, and the experiment is repeated. For difficult or complicated experiments, the result from the positive control can also help in comparison to previous experimental results. For example, if the well-established disease test was determined to have the same effectiveness as found by previous experimenters, this indicates that the experiment is being performed in the same way that the previous experimenters did. When possible, multiple positive controls may be used â if there is more than one disease test that is known to be effective, more than one might be tested. Multiple positive controls also allow finer comparisons of the results calibration, or standardization if the expected Page 3

4 results from the positive controls have different sizes. For example, in the enzyme assay discussed above, a standard curve may be produced by making many different samples with different quantities of the enzyme. Random assignment In randomization, the groups that receive different experimental treatments are determined randomly. While this does not ensure that there are no differences between the groups, it ensures that the differences are distributed equally, thus correcting for systematic errors. For example, in experiments where crop yield is affected e. This mitigates the effect of variations in soil composition on the yield. Blind experiment In blind experiments, at least some information is withheld from participants in the experiments but not the experimenter. For example, to evaluate the success of a medical treatment, an outside expert might be asked to examine blood samples from each of the patients without knowing which patients received the treatment and which did not. The blinding eliminates effects such as confirmation bias and wishful thinking that might occur if the samples were evaluated by someone who knew which samples were in which group. Double-blind experiment In double-blind experiments, at least some participants and some experimenters do not possess full information while the experiment is being carried out. Double-blind experiments are most often used in clinical trials of medical treatments, to verify that the supposed effects of the treatment are produced only by the treatment itself. Trials are typically randomized and double-blinded, with two statistically identical groups of patients being compared. The treatment group receives the treatment, and the control group receives a placebo. The placebo is the "first" blind, and controls for the patient expectations that come with taking a pill, which can have an effect on patient outcomes. Since the experimenters do not know which patients are in which group, they cannot unconsciously influence the patients. After the experiment is over, they then "unblind" themselves and analyse the results. In clinical trials involving a surgical procedure, a sham operated group is used to ensure that the data reflect the effects of the experiment itself, and are not a consequence of the surgery. In this case, double blinding is achieved by ensuring that the patient does not know whether their surgery was real or sham, and that the experimenters who evaluate patient outcomes are different from the surgeons and do not know which patients are in which group. Page 4

5 Chapter 3 : Scientific control - Wikipedia An experimental group (sometimes called a treatment group) is a group that receives a treatment in an experiment. The "group" is made up of test subjects (people, animals, plants, cells etc.) and the "treatment" is the variable you are studying. This article has been cited by other articles in PMC. We aimed to explore the prevalence of IBS, identify symptoms and contributing factors and also to examine the efficacy of trimebutine maleate in children and adolescents. Methods The study involved children and adolescents years and parents were requested to fill in a questionnaire, Rome III criteria was used to diagnose IBS. To exclude organic disease, all patients underwent medical investigations. Half of the randomly selected IBS patients were treated with trimebutine maleate while the rest of IBS patients were not. The IBS patients were reevaluated at the end of 3 weeks. Back pain OR, 6. The prevalence of functional dyspepsia in IBS group was Clinical recovery was seen in Conclusions IBS is a common disorder in children and adolescents. IBS is closely associated with somatic and familial factors. Trimebutine maleate is effective for pediatric IBS patients. Child, Irritable bowel syndrome, Trimebutine Introduction Irritable bowel syndrome IBS is one of the most common causes of recurrent abdominal pain in the pediatric population. IBS as described by the Rome III criteria includes weekly symptoms of abdominal pain or discomfort accompanied by changes in bowel patterns. We also examined the efficacy of trimebutine maleate treatment in randomly selected children with IBS in a randomized controlled study. Their ages ranged from years. The children were selected randomly. To investigate the epidemiology of IBS, their parents were asked to complete a modified version of the questionnaire on Pediatric Gastrointestinal Symptoms, Rome III version, consisting of 35 questions. Based on the questionnaire results, those patients who met the Rome III criteria, with a normal physical examination and growth curve, were pre-diagnosed with IBS. All patients underwent a complete evaluation including blood count, erythrocyte sedimentation rate, and stool examination for occult blood, leukocytes, ova and parasites independently collected 3 stool specimens were examined. The 78 patients with normal laboratory results were diagnosed with IBS and designated as the patient group. The remaining 39 patients did not take any medication. After 3 weeks, the patients and their parents were reevaluated regarding symptoms. Based on the questionnaire, cases with no abdominal pain for at least for 2 months were considered as the healthy control group. Categorical variables in the patient and healthy control groups were compared using the chi-square test. The Mann-Whitney U test was used for nominal variables. Results The study group comprised of The healthy control group comprised of The 78 patients diagnosed with IBS comprised of 47 In our study, the prevalence of IBS in patients admitted to general pediatrics clinics in our tertiary center was Figure 1 shows the distribution of abdominal pain frequency in IBS patients. In addition, gatrointestinal system symptoms in the IBS patients and healthy controls are compared in Table 1. Symptoms not related to the gastrointestinal system in the IBS patients and healthy controls are compared in Table 2. Page 5

6 Chapter 4 : Test vs. Control Group Placebo tests. A placebo is a fake treatment, such as a sugar pill. Placebos are given to the control group to account for a psychological phenomenon called the placebo effect, in which patients receiving a fake treatment still report having a response, as if it were the real treatment. That is, in randomized experiments, schools or teachers or students are often assigned at random to receive the innovative treatment the experimental group or to keep doing whatever they were doing the control group. Educators often object, complaining that they do not think it is fair that they might be assigned to the control group. Usually, schools can purchase materials and training to adopt an innovative program outside of the experiment; all the experiment typically offers is a chance to get the treatment for free, or at a deep discount. So if schools want the treatment, and are willing to pay for it, they can get it. Ending up in the control group is not so bad, either. Incentives are usually offered to schools in the control group, so a school might receive several thousand dollars to do anything they want other than the experimental treatment. Further, many studies use a "delayed treatment" design in which the control group gets training and materials to implement the experimental program after the study is over, a year or two after the schools in the experimental group received the program. In this way, having been in the control group in the short term serves to improve the school in the long run. If the methods were so proven and so widely used that not to use them would truly deprive students, then this would be unethical. IRB regulations require that the control group receive a treatment that is at least "state of the art," so that no one gets less than the current standard of best practice. The experiment is designed to test out innovations whose effectiveness has not yet been established and that are not yet standard best practice. This cycle continues indefinitely, with experimental treatments being progressively compared to harder-to-beat control treatments as evidence-based practice advances. In other words, doing experiments using control groups to improve education based on evidence would put education into a virtuous cycle of innovation, evaluation, and progressive improvement like that which has transformed fields such as medicine, agriculture, and technology to the benefit of all. Most educators would prefer not to be in the control group, but they should at least be consoled by the knowledge that control groups play an essential role in evidence-based reform. In fact, the importance of knowing whether or not new methods add to student outcomes is so great that one could argue that it is unethical not to agree to participate in experiments in which one might be assigned to the control group. In an education system offering many more opportunities to participate in research, individual schools or educators may be in control groups in some studies and experimental groups in others. As teachers, principals, and superintendents get used to participating in experiments, they are losing some of their earlier reluctance. In particular, when educators are asked to play an active role in developing and evaluating new approaches and in choosing which experiments to volunteer for, they become more comfortable with the concept. And this comfort will enable education to join medicine, agriculture, technology, and other fields in which a respect for evidence and innovation drives rapid progress in meeting human needs. If you like evidence-based reform in education, then be sure to tip your hat to the little-appreciated control group, without which most experiments would not be possible. Page 6

7 Chapter 5 : Control and Treatment Groups In the design of experiments, treatments are applied to experimental units in the treatment group(s). In comparative experiments, members of the complementary group, the control group, receive either no treatment or a standard treatment. Experimentation An experiment deliberately imposes a treatment on a group of objects or subjects in the interest of observing the response. This differs from an observational study, which involves collecting and analyzing data without changing existing conditions. Because the validity of a experiment is directly affected by its construction and execution, attention to experimental design is extremely important. Treatment In experiments, a treatment is something that researchers administer to experimental units. For example, if the experimental units were given 5mg, 10mg, 15mg of a medication, those amounts would be three levels of the treatment. Definition taken from Valerie J. Easton and John H. A factor is a general type or category of treatments. Different treatments constitute different levels of a factor. For example, three different groups of runners are subjected to different training methods. It is wise to take time and effort to organize the experiment properly to ensure that the right type of data, and enough of it, is available to answer the questions of interest as clearly and efficiently as possible. This process is called experimental design. The specific questions that the experiment is intended to answer must be clearly identified before carrying out the experiment. We should also attempt to identify known or expected sources of variability in the experimental units since one of the main aims of a designed experiment is to reduce the effect of these sources of variability on the answers to questions of interest. That is, we design the experiment in order to improve the precision of our answers. She uses the new fertilizer on one field of crops A, while using her current fertilizer on another field of crops B. The irrigation system on field A has recently been repaired and provides adequate water to all of the crops, while the system on field B will not be repaired until next season. She concludes that the new fertilizer is far superior. The problem with this experiment is that the farmer has neglected to control for the effect of the differences in irrigation. This leads to experimental bias, the favoring of certain outcomes over others. To avoid this bias, the farmer should have tested the new fertilizer in identical conditions to the control group, which did not receive the treatment. Without controlling for outside variables, the farmer cannot conclude that it was the effect of the fertilizer, and not the irrigation system, that produced a better yield of crops. Another type of bias that is most apparent in medical experiments is the placebo effect. Since many patients are confident that a treatment will positively affect them, they react to a control treatment which actually has no physical affect at all, such as a sugar pill. For this reason, it is important to include control, or placebo, groups in medical experiments to evaluate the difference between the placebo effect and the actual effect of the treatment. The simple existence of placebo groups is sometimes not sufficient for avoiding bias in experiments. If members of the placebo group have any knowledge or suspicion that they are not being given an actual treatment, then the effect of the treatment cannot be accurately assessed. For this reason, double-blind experiments are generally preferable. This eliminates the possibility that the experimenters will treat the placebo group differently from the treatment group, further reducing experimental bias. Randomization Because it is generally extremely difficult for experimenters to eliminate bias using only their expert judgment, the use of randomization in experiments is common practice. In a randomized experimental design, objects or individuals are randomly assigned by chance to an experimental group. Using randomization is the most reliable method of creating homogeneous treatment groups, without involving any potential biases or judgments. There are several variations of randomized experimental designs, two of which are briefly discussed below. Completely Randomized Design In a completely randomized design, objects or subjects are assigned to groups completely at random. One standard method for assigning subjects to treatment groups is to label each subject, then use a table of random numbers to select from the labelled subjects. This may also be accomplished using a computer. Randomized Block Design If an experimenter is aware of specific differences among groups of subjects or objects within an experimental group, he or she may prefer a randomized block design to a completely randomized design. In a block design, experimental subjects are first Page 7

8 divided into homogeneous blocks before they are randomly assigned to a treatment group. If, for instance, an experimenter had reason to believe that age might be a significant factor in the effect of a given medication, he might choose to first divide the experimental subjects into age groups, such as under 30 years old, years old, and over 60 years old. Then, within each age level, individuals would be assigned to treatment groups using a completely randomized design. In a block design, both control and randomization are considered. Example A researcher is carrying out a study of the effectiveness of four different skin creams for the treatment of a certain skin disease. He has eighty subjects and plans to divide them into 4 treatment groups of twenty subjects each. Using a randomized block design, the subjects are assessed and put in blocks of four according to how severe their skin condition is; the four most severe cases are the first block, the next four most severe cases are the second block, and so on to the twentieth block. The four members of each block are then randomly assigned, one to each of the four treatment groups. Example taken from Valerie J. Randomly selecting two individuals from a group of four and applying a treatment with "great success" generally will not impress the public or convince anyone of the effectiveness of the treatment. To improve the significance of an experimental result, replication, the repetition of an experiment on a large group of subjects, is required. If a treatment is truly effective, the long-term averaging effect of replication will reflect its experimental worth. If it is not effective, then the few members of the experimental population who may have reacted to the treatment will be negated by the large numbers of subjects who were unaffected by it. Replication reduces variability in experimental results, increasing their significance and the confidence level with which a researcher can draw conclusions about an experimental factor. Page 8

9 Chapter 6 : Control group Define Control group at blog.quintoapp.com The experimental group is exposed to a change in the independent variable to test the effect on the dependent variable. The control group and experimental group are compared against each other in an experiment. The only difference between the two groups is that the independent variable is changed in. The control group in an experiment is the group who does not receive any treatment and is used as a benchmark against which other test results are measured. This group includes individuals who are very similar in many ways to the individuals who are receiving the treatment, in terms of age, gender, race or other factors. A control group is used in an experiment as a point of comparison, so that it can be isolated in testing that the experiment did, or did not, affect the patients in the ways that were intended. Members of the control group often are given placebos and do not know that they are part of the control group so that the researcher can determine the effectiveness of what is being studied. Testing Using Control Groups In an experiment in which blood pressure medication is tested, one group is given the blood pressure medication while the control group is given a placebo pill. In a test of anxiety treatment, one group attends individual therapy sessions and receives a new medication. The control group receives only an inert pill. A treatment for drug addiction is being tested. A group of meth addicts are given the treatment while the control group is given the placebo. A treatment for hair loss in men is being tested. Men of the same age range are gathered. One group receives an application with the active ingredient while the control group receives an application that appears the same but does not have the active ingredient in it. Researchers are testing an anti-wrinkle facial product. They recruit volunteers all within the age range of and distribute bottles to everyone that appear to hold the same product. However, the control group receives bottles that do not have the compound that is intended to reduce wrinkles. Doctors are studying a weight loss drug. Volunteers for the study are recruited. All volunteers are in their thirties and are at least 50 pounds overweight. Psychiatrists are testing the effectiveness of a proposed ADHD drug. They recruit parents who are willing to allow their child to be a part of the clinical tests. All of the children are between the ages of 9 and 14 and have been diagnosed with ADHD. The psychiatrists involve the parents and the teachers in questionnaires throughout the process but only one group has the pill that is being tested while the other group of children has a sugar pill. Tests are being run to determine whether a newly developed medication can help to ease the effects of Post Traumatic Stress Disorder. Researchers recruit male volunteers aged and distribute the medication. The control group receives what appears to be the same, but is only an inert pill. Now you see how control groups are used in experiments. YourDictionary definition and usage example. Chapter 7 : 5 Differences between Control Group and Experimental Group with example Major Difference Examples of Control Groups By YourDictionary The control group in an experiment is the group who does not receive any treatment and is used as a benchmark against which other test results are measured. Chapter 8 : Why Control Groups are Ethical and Necessary HuffPost A control or control group may be defined as a group of clinical trial participants who do not receive the drug or treatment being investigated as part of the trial. To explain the above statement in simple layman's language, researchers of certain clinical trials prefer to divide the participants into 2 groups, one the experimental group and. Chapter 9 : Defining Approval Groups (Oracle Purchasing Help) Treatment Effects (Review) Definition of causal effects (estimands): differ for the control and treatment groups subject treat. crtl. treat Page 9