Establishing the significance of observed effects is a preliminary requirement for any meaningful interpretation of clinical and experimental Electroencephalography or Magnetoencephalography (MEG) data. We propose a method to evaluate significance on the level of sensors whilst retaining full temporal or spectral resolution. Input data are multiple realizations of sensor data. In this context, multiple realizations may be the individual epochs obtained in an evoked-response experiment, or group study data, possibly averaged within subject and event type, or spontaneous events such as spikes of different types. In this contribution, we apply Statistical non-Parametric Mapping (SnPM) to MEG sensor data. SnPM is a non-parametric permutation or randomization test that is assumption-free regarding distributional properties of the underlying data. The method, referred to as Maps SnPM, is demonstrated using MEG data from an auditory mismatch negativity paradigm with one frequent and two rare stimuli and validated by comparison with Topographic Analysis of Variance (TANOVA). The result is a time- or frequency-resolved breakdown of sensors that show consistent activity within and/or differ significantly between event or spike types. TANOVA and Maps SnPM were applied to the individual epochs obtained in an evoked-response experiment. The TANOVA analysis established data plausibility and identified latencies-of-interest for further analysis. Maps SnPM, in addition to the above, identified sensors of significantly different activity between stimulus types.
Electroencephalography ; Magnetoencephalography ; Methods ; Random Allocation

OBJECTIVES: In large-scale field trials, randomization by cluster is frequently used because of the administrative convenience, a desire to reduce the effect of treatment contamination, and the need to avoid ethical issues that might otherwise arise. Cluster randomization trials are experiments in which intact social unit, e.g., families, schools, cities, rather than independent individuals are randomly allocated to intervention groups. The positive correlation among responses of subjects from the same cluster is in matter in cluster randomization. This thesis is to compare the results of three randomization methods by standard error of estimator of treatment effect. METHODS: We simulated cholesterol data varing the size of the cluster and the level of the correlation in clusters and analyzed the effect of cholesterol-lowering agent. RESULTS: In intra-cluster randomization the standard error of the estimator of treatment effect is smallest relative to that in inter-cluster randomization and that in individual randomization. CONCLUSIONS: Intra-cluster randomization is the most efficient in its standard error of estimator of treatment effect but other factor should be considered when selecting a specific randomization method.
Cholesterol ; Ethics ; Humans ; Random Allocation

BACKGROUND AND PURPOSE: Mechanical thrombectomy with or without intravenous thrombolysis is indicated in the acute treatment of ischemic strokes caused by an emergent large-vessel occlusion (ELVO) within 6 hours from symptom onset. However, a significant proportion of patients are referred to comprehensive stroke centers beyond this therapeutic time window. This study performed a pooled analysis of data from trials in which mechanical thrombectomy was performed beyond 6 hours from symptom onset. METHODS: We searched for randomized controlled trials that compared mechanical thrombectomy with the best medical treatment beyond 6 hours for ischemic strokes due to ELVO and reported on between 1990 and April 2018. The intervention group comprised patients treated with mechanical thrombectomy. Statistical analysis was conducted while pooling data and analyzing fixed- or random-effects models as appropriate. RESULTS: Four trials involving 518 stroke patients met the eligibility criteria. There were 267 strokes treated with mechanical thrombectomy, with a median time of 10.8 hours between when the patient was last known to be well to randomization. We observed a significant difference between groups concerning the rate of functional independence at 90 days from stroke, with an absolute difference of 27.5% (odds ratio=3.33, 95% CI=1.81–6.12, p < 0.001) and good recanalization (odds ratio=13.17, 95% CI=4.17–41.60, p < 0.001) favoring the intervention group. CONCLUSIONS: This meta-analysis confirms the efficacy of mechanical thrombectomy in selected ischemic stroke patients beyond 6 hours from symptom onset. The selection is mainly based on the limited core infarct detected by emergent assessment using neuroimaging techniques.
Humans ; Neuroimaging ; Random Allocation ; Stroke* ; Thrombectomy*

A pilot study asks whether something can be done, should the researchers proceed with it, and if so, how. However, a pilot study also has a specific design feature; it is conducted on a smaller scale than the main or full-scale study. In other words, the pilot study is important for improvement of the quality and efficiency of the main study. In addition, it is conducted in order to assess the safety of treatment or interventions and recruitment potentials, examine the randomization and blinding process, increase the researchers' experience with the study methods or medicine and interventions, and provide estimates for sample size calculation. This review discusses with a focus on the misconceptions and the ethical aspect of a pilot study. Additionally how to interpret the results of a pilot study is also introduced in this review.
Pilot Projects* ; Random Allocation ; Sample Size

Random allocation is commonly used in medical researches, and has become an essential part of designing clinical trials. It produces comparable groups with regard to known or unknown prognostic factors, and prevents the selection bias which occurs due to the arbitrary assignment of subjects to groups. It also provides the background for statistical testing. Depending on the change in allocation probability, random allocation is divided into two categories: fixed allocation randomization and dynamic allocation randomization. In this paper, the author briefly introduces both the theory and practice of randomization. The definition, necessity, principal, significance, and classification of randomization are also explained. Advantages and disadvantages of each randomization technique are further discussed. Dynamic allocation randomization (Adaptive randomization), which is as yet unfamiliar with the anesthesiologist, is also introduced. Lastly, the methods and procedures for random sequence generation using Microsoft Excel is provided.
Classification ; Random Allocation* ; Research Design ; Selection Bias

PURPOSE: To explain the concept and procedure of random allocation as used in a randomized controlled study. METHODS: We explain the general concept of random allocation and demonstrate how to perform the procedure easily and how to report it in a paper.
Humans ; Random Allocation ; Randomized Controlled Trials as Topic/*methods

BACKGROUND/AIMS: The endoscopic injection therapy with hypertonic saline-epinephrine(HSE) and absolute ethanol are the most widely and easily used procedure in the management of patients with bleeding peptic ulcers. We performed a prospective, randomized trial to compare the hemostatic efficacy between HSE and absolute ethanol injection therapy. METHODS: During the period of 1993 to 1996, 60 patients who were identified as active bleeding or visible vessel were enrolled for this trial. The 60 patients were randomly divided into two groups(HSE group, 30 cases: ethhnol group, 30 cases). We performed endoscopic injection therapy with 3% saline and 1:10,000 epinephrine solution in HSE group, and with 99.5% absolute ethanol in ethanol group. The two groups were matched for sex, age, site of bleeding, endoscopic findings, initial hemoglobin, and concomitant illness at randomization. RESULTS: Bleeding was initially controlled in 21(70%) of the HSE group and in 29(96.7%) of the ethanol group(p < 0.05). Rebleeding occurred in 4(19%) of the HSE group and in 2(6.9%) of the ethanol group(p < 0.1). The ethanl group achieved a better hemostatic effect for spurting hemorrhage(3/13 vs 9/10, p < 0.05). The emergent operations were undergone in 10(33.3%) and 2(6.7%) for HSE group and ethanol group respectively(p < 0.01). The stay in hospital were less than in ethanol group(mean 9.5 vs 16.3, p < 0.01). The death were noticed in 6 cases(20%) in HSE group and 1 case(3.3%) in ethanol group(p < 0.05). CONCLUSIONS: This study shows that absolute ethanol injection is more efficaceous and better satisfactory method in peptic ulcer bleeding.
Epinephrine ; Ethanol* ; Hemorrhage* ; Humans ; Peptic Ulcer* ; Prospective Studies ; Random Allocation

PURPOSE: A low quality clinical trial could produce errors, and these errors could, in turn, distort the results of the clinical trial. To avoid applying distorted results of trials clinically, a quality analysis of clinical trials is needed. MATERIALS AND METHODS: We selected randomized controlled trials (RCTs) about erectile dysfunction (ED) conducted in Korea using Medline and KoreaMed. Quality assessment of selected RCTs was performed using three assessment tools (Jadad scales, van Tulder scale, Cochrane Collaboration Risk of Bias Tool [CCRBT]). RESULTS: The first RCT about ED conducted in Korea was published in 2002. Since 2002, a total of 20 RCTs have been published in medical journals. Among the 20 articles, only 1 article was found to have a low risk of bias according to the CCRBT. On the Jadad scale, there were 17 high quality articles, while 19 articles were assessed as high quality by the VTS. Only 2 RCTs described the randomization method adequately. Only 1 RCT presented allocation concealment. CONCLUSIONS: A low quality clinical trial could produce errors, and these errors could, in turn, distort the results of the clinical trial. To avoid applying distorted results of trials clinically, a quality analysis of clinical trials is needed. The quality of RCTs was found to be high because almost all of the selected RCTs were double blinded studies. However, the quality of RCTs was inadequate with regard to the lack of randomization and absence of allocation concealment. Therefore, performing adequate randomization and adding a description of the appropriate concealment of allocation may improve the quality of RCTs.
Bias (Epidemiology) ; Erectile Dysfunction ; Korea ; Male ; Random Allocation

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common condition. However, many of the traditional therapies like monotherapy used in clinical practice fail to show efficacy. There is no one particular treatment to be recommended as monotherapy for CP/CPPS. The new concept of treatment which is ‘UPOINT’ is introduced. The major barrier in treating men with CP/CPPS is the heterogenous nature of this syndrome. In order to treat appropriately, the patient should be evaluated individually to assess the nature of symptoms. To evaluate patients with chronic urologic pelvic pain, a six-point clinical phenotyping system has been developed. The clinical domains are urinary symptoms, psychosocial dysfunction, organ specific findings, infection, neurologic/systemic, and tenderness of muscles, which produces the acronym ‘UPOINT’. This clinical phenotyping system may provide a useful and clinically relevant framework for multimodal therapy for the treatment of CP/CPPS. However, the concept of UPOINT needs randomization, placebo or sham control studies to show verified treatment.
Humans ; Male ; Muscles ; Pelvic Pain* ; Prostatitis ; Random Allocation

OBJECTIVE: To test the null hypothesis that SmartClip self-ligating brackets are more effective than conventional brackets for initial mandibular alignment and identify influential factors. METHODS: Fifty patients were randomly allocated to two equal treatment groups by using an online randomization program: self-ligating group (SmartClip brackets) and conventional group (Gemini brackets). The archwire sequence was standardized. Changes in anterior irregularity index, intercanine width, and intermolar width were assessed on plaster models at 8th and 16th weeks. Changes in incisor position and inclination were assessed on lateral cephalometric radiographs at 16 weeks. Intragroup and intergroup comparisons were performed with paired t-test and Student's t-test, respectively. Multiple linear regression was performed to identify variables affecting improvement in anterior ambiguity. RESULTS: Data of 46 patients were analyzed; those missing an appointment (n = 2) or showing bracket breakage (n = 2) were excluded. Incisor inclination (p < 0.05), intercanine width (p < 0.05), and intermolar width (p > 0.05) increased at 8 and 16 weeks in both the groups; no significant intergroup differences were noted (p > 0.05). Initial anterior irregularity index and intercanine width change were significantly associated with improvement in anterior irregularity (p < 0.001). CONCLUSIONS: The null hypothesis was rejected. Bracket type has little effect on improvement in anterior ambiguity during initial mandibular alignment.
Humans ; Incisor ; Linear Models ; Prospective Studies* ; Random Allocation