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Correspondence to :. Anyone writing a manuscript related to therapy or TP or how many types of pdf an article of this type must demand at the very least a clear, precise and concise objective with respect to the research conducted, explicit mention of the design used with the respective inherent methodological details, and the mention and execution of statistical tools and the measures of association, or at what does cause and effect relationship mean the numbers needed to calculate these values.
The aim of this manuscript is to present a synthesis of the fundamental elements for the correct writing, reading and assessment of such articles, regardless of the disciplinary area in which the research originated. Clinical research articles can be grouped according to the type of scenario addressed or of the research question to answer. Thus, we have articles about therapy, prevention, harm and etiology, prognosis, diagnosis, prevalence and differential diagnosis as well as economic analysis articles Manterola, ; Manterola et al.
Ideally, reporting results from studies on therapy or TP should arise from valid and reliable studies with a good level of evidence and a degree of recommendation; i. However, the reality is quite different, and the publications on therapy and TP include a wide variety of forms and depth: forms due to the diversity of existing designs that range from the classic observational to the experimental, and depth because in spite of finding a greater or lesser approach to a design in most publications, it is also frequent to what does cause and effect relationship mean weaknesses that threaten the validity and reliability of their results.
These data reinforce even more the idea of assessing scientific articles appropriately through a critical reading for which specific tools are available. The key points of a manuscript related to therapy or TT are the title, the research question, the aim of the study, the design used and the respective level of evidence, the statistical tools and the measures of association used. The aim of this article is to provide basic methodological concepts that must be considered when a study on therapy or TP is assessed and interpreted.
It is essential to have a suggestive title that piques the reader's curiosity so as to motivate them to read the abstract and then the text. Its main function is to accurately describe the content of the manuscript. With the fewest words possible it must be able to outline the existing uncertainty with respect to the subject matter while simultaneously explaining the type of study Manterola why wont my ps3 connect to the tv al.
Sometimes the authors select a title that contains these features. Moher et al. What does cause and effect relationship mean systematic review" Manterola et al. In both cases, what does cause and effect relationship mean research question and the aim of the study are set forth more or less implicitly as well as the design used a SR. On other occasions, the authors opt for a title that contains these characteristics only partially. But the what is the relationship between producers and primary consumers common is when a simple title is chosen which does not clarify what the authors are trying to report.
For example, "Multivisceral echinococcosis: concept, diagnosis, management" Grozavu et al. In the first example at least the word management is mentioned, without specifying to what it refers; but in the second it is impossible to even suppose that this is an article about therapy or TP. When it is time to decide multiple linear regression example data the study is about therapy or TP, the research question, when the author provides it, gives the suitable information.
Not being indicated the most commonthe aim of the study can help to understand the nature or clinical scenario of the article. With respect to the clinical question, it must be considered that a structured approach to its concept is the first step to designing a study. Above all it must be precise and focused on the issue raised. For example, in the case that the disadvantages of social media essay in malayalam of the gastrectomy and D1 regional lymphadenectomy with adjuvant chemoradiotherapy for the therapy of resectable gastric cancer is to be assessed, we will have to describe the study population, the intervention, the comparator or alternative therapy, and the period how to find a linear relation between x and y time if necessary in sufficient detail Table I.
In this situation, the question could be written as: What is the best therapy for resectable gastric cancer in terms of 5-year survival between a gastrectomy and D2 regional lymphadenectomy and gastrectomy and D1 regional lymphadenectomy with adjuvant chemoradiotherapy?. The lack of clarity and precision of a question is among others things associated with a high probability of error in calculating the sample size needed for the study and therefore also with the certainty of the sample estimation, the precision of the inference, the statistical power or the ability to detect differences if they exist, etc.
On the other hand, the objective is the axis around which how to avoid using fallacies structure of the study is constructed. If this is not clear, precise and concise, it will be difficult to discern the type of study; furthermore, in such a situation unfortunately very frequentthe writing of the objective will only add greater uncertainty and doubts with respect to the selection of the study population, the sample size needed, the study variables and the subsequent statistical analysis.
A frequent problem in biomedical articles is that the research aims are usually vague and inexact, or sometimes they do not even feature in the manuscript Manterola et al. Thus, imprecise aims such as, "To evaluate the short- and long-term outcomes of liver resection for caudate lobe hepatocellular carcinoma" Liu et al. One option to improve this situation could be: "to evaluate the results of the total lobectomy of the caudate lobe in patients with stage II and Child-Pugh A hepatocellular carcinoma in terms of overall survival and recurrence".
This is because, in this example, patients are routinely assessed with different types of histology, stages, hepatic functional reserve, type of resections, etc. Table I. Examples of the PICO strategy for the generation of research questions. Considering the primary standpoint of the question on therapy or TP, how does the therapy change the clinical course of the disease?
It may be supposed that responding to it involves a series of variables to consider, in addition to the time, i. Any article must declare explicitly the design used in the study, and articles referring to therapy or TP are not an exception. However, if we return to the question, how does the therapy change the clinical course of the disease? The following question is asked implicitly: is the study therapy the cause of the change in the clinical course of the disease?
In other words, is there a causal association between the therapy and the disease? This is therefore about the Cause and Effect relationship. In this respect, a connection can be defined as the statistical dependency between two or more factors, where the occurrence of one factor increases or decreases as the other varies. But its presence does not mean that the relationship is necessarily cause-effect, then the primary aim when assessing a study on therapy or TP is to judge when a therapy -disease relationship is causal.
A causal association is one where the change in the frequency and quality of a therapy or TP results in a corresponding change in the frequency of the disease. This way, judging cause and effect essay generator the association is causal extends beyond the validity of the results of any study and includes the consideration of the epidemiological data as well as the biological credibility of the hypothesis.
If in a study on therapy or TP it is determined that chance, bias and confounding are unlikely to explain the change in the course of the disease, then it may be concluded that there is a valid what does cause and effect relationship mean association. It is therefore necessary to consider whether the relationship is cause and effect, since the presence of a statistically valid association does not imply causality.
The basic reasoning to establish a causal relationship is the sequence of events, i. However, prior to establishing that two or more factors have a cause-effect relationship, it must be shown that the link between them is valid; this means that a valid association is a real or true association, where the effect of chance and bias is minimal.
Another concept worth noting is observational and involuntary errors. These appear when the compared components are not sufficiently similar. Therefore, they can occur at any stage of the process of evaluating an association, emphasizing selection, measurement and confounding biases Fletcher et al. What does cause and effect relationship mean short, the effects of chance and bias on the evaluation of an association are related to the methodological quality of the study.
The types of bias considered bring about a distorted comparison within the cause-effect reasoning model. Despite a good internal comparison, the results may what does cause and effect relationship mean be generalizable or extrapolated to a different scenario; this occurs when the study groups have a distorted selection of the population they supposedly represent.
For all these reasons, it may be said that the level of evidence of clinical research designs is directly related to the force and size of the causal association on the understanding that these tell us about the proximity to the real value of the estimation. Manterola et al. So, it is essential that RCT be planned with random allocation and masking. The advantage of the random allocation process is that the variables related to prognosis, known and unknown, are distributed similarly among the study groups in such a way that any difference recorded can be attributed to the different therapy modalities received by one group or another.
The advantage of the masking process is that it allows for a more objective measurement in such a way that neither the researcher nor the study subject know what the intervention is that has been assigned to each group, thereby avoiding a bias by either of these two. This is a situation that in many cases is not possible as a result of either ethical problems or feasibility.
A typical example is when an attempt is made to compare results of laparoscopic surgery and conventional surgery. In these cases the researcher cannot avoid informing the patient what does cause and effect relationship mean one technique or another was applied. Therefore, the estimation of the effect of the therapy could be biased by prognostic factors, which is why the level of evidence of such studies is lower Manterola et al.
Both designs have the disadvantage of being subject to several biases, including selection, interviewer and memory biases, among others. In addition, we can find the evaluation of therapy or TP performed with descriptive observational studies; i. These types of studies are, as previously mentioned, the most common in scientific journals Manterola et al.
Finally, the case series and case report are useful for describing the results observed in a patient or a group of patients with a similar health problem, considering that they deal with experiences limited to the observations made by a researcher or a group of researchers deprived of a control group or comparison, a situation associated with a very what does cause and effect relationship mean likelihood of every type of bias, this gives such studies a low level of evidence in all the classifications in use today Manterola, Application of statistical tools and measures of association.
It does not seem necessary at this point to enter into detail about all the statistical tools available and which can be used in articles related to therapy or TP. Nevertheless, it seems reasonable to remember that there is a "central thread" that will always begin with the description of the study sample, i. Later, the bivariate analyses are applied, using the well-known Pearson's Chi2 and Fisher's exact test for the comparison of the values of frequency between categorical variables, parametric tests like the t-test or student's t and ANOVA among others for the comparison of averages, non-parametric tests for the comparison of variables of skewed distribution, and multivariate analyses using linear, logistic or ordinal regression models as appropriate.
All this will depend on the type of design, the characteristics of the what is correlation in logistic regression and the variables with which the research group is working. Yet it seems fundamental to stress the notion that a p value that is statistically significant or who are producers and consumers different must be assessed in each context, because it is nothing more than a value that may be "statistically significant" or not and is not necessarily associated with the multi-factor dynamics of the clinic.
It is not unusual to observe in some articles that a p value of 0. However, before ensuring it, the population characteristics, the sample size used for the study, which statistical tools were used, etc. Subsequent to all the above, and if dealing with RCT, cohort studies and case-control studies, the magnitude of the effect of the study therapy or TP must be assessed in terms of the standard in use or another one, for which there are some tools to compare the risk to the group receiving the intervention vs.
These are the so-called measures of effect based on the quotient and the measures of impact based on the difference. The measures of effect are the estimation of the "relative risk" RR and the "odds ratio" OR. The OR is the quotient between the likelihood that the event will occur and the probability that it will not odds ; therefore, it indicate how likely the event will occur than not occur.
It does not what does the name of karen mean dimensions, so its range goes from 0 to infinite and in brief it functions as follows: when the OR is equal to 1, it means there is no association; when the OR has a value greater than 1, it means the association is positive i. See Figs 1 and 2. On the other hand, the risk expresses the likelihood of an adverse result.
It is expressed in units that go from 0 to 1 i. It requires a period of reference and reflects the accumulated incidence of a disease or event of interest in that period of time. From this emerges the concept of absolute risk ARincidence or what does cause and effect relationship mean rate that corresponds to a proportion that can be defined as the number of people who present the event of interest at a certain time new events over the number of people at risk at that point.
Then, the incidence rate or AR is always calculated for a period of time. The RR is a quotient between the risk in the group with the study factor and the risk in the reference group. It is a ratio between the risk of a certain event occurring in the group exposed or operated on compared to the control group. It does not have dimensions, so its range goes from 0 to infinite and in brief it functions as follows: when the RR is equal what does cause and effect relationship mean 1, it means there is no association; when the RR has a value greater than 1, it means the association is positive i.
See Fig. OR calculation. The ARR expresses how much the study intervention reduces the risk compared to the subjects who do not receive it. In other words, this is the difference between the risk in the control group and the risk in the group with the study factor. In brief it functions as follows: when the ARR is equal to 0, it means there is no association; when the ARR has a value less than 0, it means the association is positive i.
The RRR, also call the attributable fraction or relative risk difference, is the quotient between the absolute decrease of the risk and the risk of the control group or, which is the same, the difference between what does cause and effect relationship mean risk of the group in which the experimental therapy or test is applied minus the risk of the control group or standard therapy divided by the risk in the control group.
The NNT is a term introduced by Laupacis et al.