This research has investigated The study set out to The purpose of the present research was to The study has shown that An important finding to emerge in this study is The results are significant in three respects In general, therefore, the results show The findings add to our understanding of Oct 27, · The results chapter of a thesis or dissertation presents your research results concisely and objectively. In quantitative research, for each question or hypothesis, state: The type of analysis used. Relevant results in the form of descriptive and inferential statistics. Whether or not the hypothesis was supported In any research as important is to detect significant differences in a particular comparison, as it is the finding of no statistically significant results, and therefore should be discussed
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Try out PMC Labs and tell us what you think. Learn More. Optimism bias refers to unwarranted belief in the efficacy of new therapies.
We assessed the impact of optimism bias on a proportion of trials that did not answer their research question successfully, and explored whether poor accrual or optimism bias is responsible for inconclusive results.
Retrospective analysis of a consecutive series phase III randomized controlled trials RCTs performed under results of a dissertation research study are inconclusive aegis of National Cancer Institute Cooperative results of a dissertation research study are inconclusive. Investigators consistently overestimated their expected treatment effects, but to a significantly larger extent for inconclusive trials.
The median ratio of expected over observed hazard ratio or odds ratio was 1. Optimism bias significantly contributes to inconclusive results. Optimism bias refers to unwarranted belief in the efficacy of new therapies, and significantly contributes to inconclusive results. Formal statistical inference alone is not sufficient to answer the research question. The answers to the research question also depend on subjective judgments, which at times are in conflict with statistical inference.
How often and why results from randomized clinical trials are inconclusive, and whether there is a concordance between statistical inferences and investigators global judgments in phase III randomized controlled trials is not known. This is the first empirical study to show the reasons for inconclusive findings. Trial design should not rely on an intuitive approach but should include a detailed rationale for the chosen effect size, ideally based on systematic review of the existing evidence on the topic.
In the conduct of randomized controlled trials RCTethical and scientific principles require a reasonable expectation that the research questions will be answered, thus contributing to general knowledge resulting in societal benefit.
The proportion of RCTs in oncology that generates reasonably conclusive statements is unknown. Theoretically, two reasons can be offered as explanations for publications of inconclusive trials: a inadequate patient accrual [ 8 ] b optimism bias- an unwarranted belief in the efficacy of new treatments[ 9 ].
By overestimating the treatment effect of a particular therapy, trials are designed with insufficient power to detect the actual, smaller treatment effects between tested therapies. In determining whether a trial provides conclusive results, researchers usually use two inferential approaches: 1 hypothesis-driven, formal statistical or mathematical rules aimed to assess the impact of the experimental treatment on the primary outcome of interest in comparison to a control, and 2 global, subjective, assessments of the relative merits of the treatments, which are based on an integration of various factors including data from non—primary endpoints and external factors such as treatment toxicity, ease of application, resource use, etc.
Information on the extent to which these two inferential approaches influences published conclusions in clinical trials is lacking. We sought to examine how frequently completed phase III oncology trials generate conclusive results, to quantify the impact of optimism bias on trial results, and to assess the nature of inferential processes underlying the conclusions drawn from a trial.
Given the important role of the NCI-funded Clinical Trials Cooperative Groups in advancing cancer care, we elected to focus our study on phase III oncology trials performed by these groups. Details regarding publication status, quality and overall distribution of outcomes from these trials have been reported elsewhere.
Conclusive trials included trials with a statistically significant result, results of a dissertation research study are inconclusive. Thus, we considered statistically significant favoring new or standard treatment and true negative results as conclusive findings and all other results to be inconclusive. Figure 1 illustrates the methods used to determine the designation of conclusive and inconclusive trials. Classifying results from RCTs as true negative, positive or inconclusive, results of a dissertation research study are inconclusive.
Adapted from Alderson, P. BMJ ; — Since minimally important clinically meaningful treatment differences were rarely specified in the protocols, we based the pre-determined limits of equivalence on published estimates related to what can be considered small, moderate, or large treatment effects in oncology.
These judgments were categorized using a 6 point scale previously shown to have high face and content validity and high reliability. Flow chart describing the selection of studies. Several definitions were used to establish concordance between statistical calculations and investigator judgment.
The results were also deemed concordant if category III judgments were matched with true negative and inconclusive results according to statistical criteria [ 15 ]. All other combinations of statistical calculation and investigator judgment were considered discordant.
Details of this classification scheme are presented in Figure 3. Extracted data included expected and observed treatment effects, results of a dissertation research study are inconclusive, predicted and actual patient accrual, pre-trial power calculations, pre-trial estimates of treatment effects the expected difference between the treatments and sample results of a dissertation research study are inconclusive calculations.
Treatment effects were typically expressed either as relative effects e. HR of 0. To allow comparisons between different ways of reporting predicted and observed effects, differences expressed in absolute terms were converted into relative effects.
All results were normalized for reduction of bad outcomes i. To obtain a more intuitive comparison of expected versus observed treatment effects, given that lower HR or OR indicates a larger treatment effect, we expressed the results as the inverse ratio of HR or OR calculated using results of a dissertation research study are inconclusive following formula:. Although all trials included in our analyses were considered complete, theoretically the use of ratio may underestimate our findings, because the distribution of observed effects in statistically inconclusive studies will likely be closer to one that those for conclusive studies.
Nevertheless, we believe the use of ratio represents the most intuitive measure to address our hypothesis. The results of a dissertation research study are inconclusive provides a distribution of the results without employing division of expected with observed results. In most cases, researchers did not postulate a single therapeutic effect but, rather, gave a range of treatment effects.
Therefore, to determine results of a dissertation research study are inconclusive lowest expected treatment effect which would meet the criterion of minimally important differences within the range of postulated treatment effects, we extracted the α and β values and their corresponding z-values for each trial. We then calculated the adjusted expected HR or OR by multiplying the originally stated expected HR or OR by the following formula where Z represents the standard Z-statistic :.
These adjusted expected effects were then compared with the observed effects from the publications. In addition, the ratio of the predicted and actual patient accrual number was used to determine if poor accrual might have contributed to inconclusive results.
Data on predicted and observed treatment effects, power calculations, and accrual statistics were also used to explain discordance between statistical calculations and investigator judgments. We looked in particular for any statements to support this divergence. Mann-Whitney U non-parametric test statistics was used for all comparisons. All analyses were done using the SPSS statistical software package. Sponsors had no role in design, data collection, data analysis, or interpretation of this study, and were not involved in writing this report or in the decision to submit it for publication.
This yielded separate comparisons. we retain only one, clinically or statistically, most significant comparison in the analysis. Therefore, this report is based on comparisons trials enrollingpatients Figure 2.
In 19 of these 95 instances, investigators concluded that one treatment was superior or equal to another, while the statistical findings supported the opposite conclusion. The most frequent reasons for this discordance were the toxicity with the new treatment, lack of meaningful clinical benefits, and ease of drug administration see Appendix.
As Figures 4a and b illustrates, researchers consistently overestimated the treatment effect across all trials. Figure 5 shows the distribution of expected vs. observed results in relation to statistical criteria. The median ratio of observed over expected HR was 1.
Figure 6 shows the distribution of expected vs. observed results in relation to patient accrual. The patient accrual did not significantly affect investigators over-optimistic estimates.
Neither treatment effects observed vs. expected nor sample size planned vs, results of a dissertation research study are inconclusive. actual accrual have changed over time see Appendix. Additional analyses using adjusted expected HR did not change these results in any important ways.
HR-hazard ratio, OR-observed ratio. Note that in Fig 4b HR represents HR or OR. Results are shown as the ratio of the observed HR or OR divided by the expected HR or OR. deaths instead of survival. Thus, a lower HR or OR indicates a larger treatment effect on a bad outcome. For example, an expected HR of 0. A ratio of 1 means that the expected treatment effect was the same as the observed one, and a ratio below 1 would indicate that the investigators observed a larger effect than expected the log transformation is used for better display.
The distribution of treatment effects expressed as hazard or odds ratio and shown as the percentage difference between expected and observed results.
The line at zero indicates that observed results perfectly matched expected treatment effects. The negative numbers indicate the extent percentage above which expectation exceeded the observed effects. The positive findings indicate the percentage above which actually observed results exceeded expectations. The distribution of expected vs. The appendix provides additional results of interest.
As depicted in figure 7our review of research protocols showed that in many trials the design was disproportionally driven by unrealistic expectations. Distribution of categories of expected versus observed treatment results of a dissertation research study are inconclusive across trials, results of a dissertation research study are inconclusive. As it can be seen, there is a tremendous discrepancy over the entire range of treatment effects between what investigators expected and what they actually observed.
This failure to provide relatively convincing answers to questions addressed in trials may represent a waste of precious resources and a possible ethical breach of the contract with patients who expect that answers from clinical trials will help future patients. We conclude, therefore, that optimism bias — the unwarranted belief in the efficacy of new therapies — contributed significantly to the inconclusiveness of trials.
As a consequence, the inconclusive comparisons were also noted to have smaller average predicted accrual targets. Alternatively, the investigators may have actually estimated the treatment effect correctly, but to function in logistical constraints of patient recruitment or funding they might have adjusted the power calculations, results of a dissertation research study are inconclusive.
That is, realistic calculations may show that the required accrual is difficult or impossible to accomplish given an existing fixed budget. Trial design cannot rely on an intuitive approach but should include a detailed rationale for the chosen effect size, ideally based on systematic review of the existing evidence on the topic.
Furthermore, awareness of the prevalence of optimism bias and its impact on trial design may encourage more realistic, albeit smaller treatment effects estimates. Such modifications to the originally proposed hypotheses are considered epistemologically less valuable than hypotheses-driven predictions[ 29 ].
However, our previous evaluation of results of a dissertation research study are inconclusive quality of these trials according to methodological dimensions that have been empirically linked to bias such as quality of randomization procedure, the magnitude of drop-outs, employment of blinding, use of intention-to-treat analysis etc [ 30 ] showed the NCI COG trials of high quality,[ 31 ] indicating no obvious bias.
effects of treatment on the primary outcomewhile investigators evaluate treatment effects across many dimensions. Of interest, recently Booth et al [ 33 ] analyzed differences between conclusions of the abstracts of RCTs presented at major oncology meetings with the subsequent final analyses published in full papers. Our findings have important implications not only for researchers drawing conclusions about the results of their own trial, but also for the interpretation of evidence of relevance to clinical practice and policy decision-making e.
How to Write a Dissertation Results Section - Scribbr ��
, time: 3:54Optimism bias leads to inconclusive results - an empirical study
Oct 27, · The results chapter of a thesis or dissertation presents your research results concisely and objectively. In quantitative research, for each question or hypothesis, state: The type of analysis used. Relevant results in the form of descriptive and inferential statistics. Whether or not the hypothesis was supported Next, this does NOT necessarily mean that your study failed or that you need to do something to “fix” your results. Rest assured, your dissertation committee will not (or at least SHOULD not) refuse to pass you for having non-significant results. They will not dangle your degree over your head until you give them a p-value less than Further, blindly running additional analyses May 14, · Views Researchers decide whether or not to publish a study based on the final outcomes. They are more likely to report findings that are positive and similar to those previously reported in literature. Null, insignificant, or inconclusive results often stay hidden in lab notebooks, never to be published! Some researchers on the other hand, in a bid to get
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