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At least 19 recordsLinked to original sources
PubMed1979

Intra- and interhemispheric EEG differences quantified by spectral analysis. Comparative study of two groups of schizophrenics and a control group.

In this work we have studied comparatively the relationships between alpha intensity, alpha frequency, root-mean-square amplitude and their standard deviations, versus the location of the four recorded EEG channels: left and right rolando-parietal, left and right parieto-occipital. Twenty-four spectral parameters were computed for each 5-min EEG recording, in the eyes closed situation. The hebephrenic group (36 EEGs from six patients) presented higher values of alpha intensity and RMS amplitudes with low coefficient of variation when compared with the other groups. The left/right rolando-parietal amplitude ratio was 0.73 versus 1.52 for the parieto-occipital ratio. An amplitude hypovariability in the central regions, probably associated with hyperarousal, especially in the left hemisphere, can then be observed in hebephrenics, together with high alpha intensity on the left parieto-occipital area. The two groups of schizophrenics differ from the control group (27 EEGs from 12 subjects) in terms of spectral parameters, the hebephrenic group presenting a possible interhemispheric dysfunction.

Adult↗
PubMed1979

[Use of the control group selected by a method of matched samples in the evaluation of the health status of children from complicated pregnancies].

A method of matched samples consisting in selection of "a partner" for each examined individual according to the established criteria of similarities is one of the methods used owing to its apparent organizational ease in selecting of the control group. The control group selected in this way was used in the evaluation of the effect of bleeding during the first 16 weeks of pregnancy on the health status and physical development of children. The paper points out the advantages of using the control group selected by the method of matched samples. It also presents the difficulties encountered in practice. Typical of this study technical methods and statistical tests used in evaluation of the results were juxtaposed and discussed, then compared to those used when a group was randomly selected. Special attention was paid to 3 basic problems: Time stability is selection of criteria for matched samples. Adjustment of age differences within pairs. Two methods were used for comparison of the anthropometric measurements. The first one consisted in levelling of the differences by the method of regression, the second in the use of various available growth curves. The results obtained by both methods were compared by means of statistical tests. The third problem concerned adequacy of the tests used when the control group was selected by the method of matched samples. Results obtained by application of t-Student test for paired samples were compared to those obtained by t-Student test for independent variables. The merits of the method of matched samples were presented using some examples (table I, II, III). Eleven conclusions were drawn from evaluation of suitability of selecting the control group according to the method of paired samples. These can be put into three main groups: Showing in what kind of studies the control group selected by the method of matched samples is payable . Showing various inconveniences caused by selection of the control group by the method of matched samples, Conclusions concerning methodological or other benefits drawn from this method. It is clearly indicated in this paper that the control group selected by the method of matched samples is recommended only in certain investigations. Before the final decision is taken all pros and cons should be considered.

Anthropometry↗
PubMed1990

Effects of intravenous cibenzoline on ventricular vulnerability and electrophysiology in patients with sustained ventricular tachycardia in comparison to a control group.

The electrophysiologic effects of intravenous (i.v. 1.5 mg/kg) cibenzoline were investigated in 13 patients with organic heart disease and supraventricular arrhythmias (control group) and 13 patients with drug refractory sustained ventricular tachycardia (VT group). In both groups, cibenzoline increased the effective refractory period (ERP) of the right ventricle (p less than or equal to 0.05), QRS duration (p less than or equal to 0.01), and QTc duration (p less than or equal to 0.01). Cycle length of the VT was increased from 311 +/- 73 to 393 +/- 119 ms (p less than or equal to 0.05) as well. The increase in QTc duration was more pronounced (p less than or equal to 0.05) in the VT group as compared with the control group. In four patients in the VT group with the largest increase in QRS-, QTc duration and cycle length of the VT proarrhythmia was noted after i.v. cibenzoline. Cibenzoline plasma levels were not significantly different between the two study groups. In the VT group, induction of VT was prevented in 2 patients, more difficult in 2 patients, easier in 1 patient, and unchanged in 5 patients. Spontaneous occurrence of the VT or induction by atrial stimulation was noted in 4 patients. In the control group, ventricular vulnerability remained unchanged. Cibenzoline may be effective in selected patients with drug refractory VT. In such patients, the increase in QTc duration was more pronounced as compared with a control group.

Anti-Arrhythmia Agents↗
PubMedDate not supplied

[Gamma-glutamyltranspeptidase in chronic polyarthritis. I. Comparison with a control group and relationship with alkaline phosphatase].

Gamma-GT, alcaline phosphatase and other parameters of abnormal liver functions were estimated in 54 consecutive in-patients having active RA but without a previous history or clinical signs of liver disease, and compared with a matched control group, suffering from degenerative rheumatic disease. There was a slight to moderate elevation of gamma-GT in 40.4% of the RA-patients (mean value 27.2 IU/l) and in 32.1% (mean value 22.3 IU/l) of the control group, respectively. The difference was not significant. Abnormal values in the control group occurred mainly in patients with peri-arthropathia of the shoulder, before mobilisation under anaethetic (3 of 5) and - coxarthrosis before total hip replacement (4 of 12). Alkaline phosphatase was elevated in 25.9% of the RA-patients (mean value 41.3 +/- 21.9 IU/l) and in 14.8% of the control group (mean value 34.3 +/- 15.9 IU/l). The difference was significant. There was a correlation between gamma-GT and alcaline phosphatase in the RA-group (r = 0.549, p less than 0.001) but not in the control group (r = 0.102). Abnormal values found in the control group were mainly found among patients with osteoporosis, following fractures, and coxarthrosis. The frequency of abnormal results and the value of the means increased with raising disease activity. Two groups of 30 and 32 patients, respectively, were examined at intervals of 2 or 4 weeks over a period of 6-10 and 18 months, respectively, and showed temporary elevations os gamma-GT in 3/4 of all patients, of GOT in 2/3 of alcaline phosphatase in 1/2 and of GPT in 1/3. Compared with other parameters of liver disease gamma-GT did not react in a different but in a more sensitive way. In our opinion it is the most sensitive indicator of reactive changes of the liver in RA.

Adult↗
PubMed1992

The control group conundrum in chronic pain case/control studies.

The choice of an appropriate control group has been recognized as one of the most difficult problems in the methodology of case/control studies, both in theory and in practice. In the study of chronic pain, a "well control group" has frequently been employed. Although this design has intuitive appeal, it contains the potential for bias and error. In order to obtain the proper control group, the same exclusion criteria should be applied to cases and controls. Second, controls should be selected independently of exposure to the putative risk factors under investigation. To illustrate the nature of this problem we present two numerical examples, using a chronic pain disorder.

Case-Control Studies↗
PubMed1992

Impact of a matched term control group on interpretation of developmental performance in preterm infants.

One hundred twenty-four children who were born at 24 to 31 weeks' gestation and 124 term children matched in social background underwent serial developmental evaluations. The Bayley Mental Developmental Index at 6, 15, and 24 months and the McCarthy General Cognitive Index at 4 years were used to classify cognitive outcome for preterm children as normal (indices higher than 1 SD below the mean), mild-moderately delayed (indices between 1 and 2 SD below the mean), or severely delayed (indices > or = 2 SD below the mean). Classifications based on norms derived from the performance of the term control group were compared with those based on published standardized test scores. The control group had substantially higher mean (+/- SD) Bayley Mental Developmental Indices at 6 (111 +/- 11), 15 (114 +/- 13), and 24 months (115 +/- 21) than the published test mean (100 +/- 16). Consequently, significantly more preterm children were classified as normal when the Bayley test mean was used than when the performance of the control group was used to define the normal range (84% vs 52% at 6 months, 82% vs 49% at 15 months, and 70% vs 47% at 24 months). Severe cognitive delays were infrequent when defined by test mean (6% to 11%) but two to three times greater when the control group scores were used. In contrast, the control group had a mean McCarthy General Cognitive Index at 4 years (102 +/- 14) that was similar to the published test mean (100 +/- 16).(ABSTRACT TRUNCATED AT 250 WORDS)

Child Development↗
PubMed2026

Does Inquiry-Based Learning Improve Students' Critical Thinking? A Meta-Analysis Accounting for Control Group Variations.

BACKGROUND: Inquiry learning is widely recognized, through empirical studies, as an appropriate instruction in enhancing students' critical thinking, yet the results were varied across context. The previous meta-analysis did not include the control group variations as a potential moderator and the studies subject domain was limited only to science subjects. Consequently, it is difficult to generalize the effectiveness of IBL in enhancing critical thinking. This meta-analysis aims to investigate whether inquiry learning is effective in improving the students' critical thinking skills and examine the moderating roles of each study characteristic. Methods The literature search applying the PRISMA protocol 2020 was conducted by utilizing SCOPUS, ERIC, and DOAJ databases. A total of 57 studies from 51 articles, published from 2015 to 2025, were synthesized using a random-effects model with standardized mean difference (SMD). RESULTS: The analysis revealed that IBL has a large and significant effect on enhancing students' critical thinking (g = 1.336; 95% CI [1.061, 1.611]). However, substantial heterogeneity was observed (I 2 = 92.09%), suggesting variability across contexts. Moderator analyses revealed that the main moderator, control group variations, was statistically significant in moderating the effectiveness of IBL (Qm = 5.21; p = .022). in contrast, subject domain (Qm = 1.43; p = .698), education level (Qm = 1.11; p = .774), and country ( Q m  = 3.33; p = .650), were insignificantly moderating the effectiveness of inquiry learning. CONCLUSIONS: The present meta-analysis highlighted that IBL is effective in improving students' critical thinking. However, the effectiveness of IBL was relative to the type of control group variations. Its effect on critical thinking was greater when compared with teacher-centered learning but smaller when compared with other student-centered learning.

Thinking↗
PubMedDate not supplied

Reducing sample sizes when comparing experimental and control groups.

In comparing rates for two groups (one control and the other experimental), one may use an historical control to reduce the sample size needed for a test of significance to one-fourth that required if the control is not historical. If there is some doubt as to whether one's control is comparable to the historical control, a test showing the equality of the historical and experimental controls can lead to a halving of the sample required for significance testing. This same argument also applies to the comparison of two means.

Research Design↗
PubMed1978

Mucosal-associated bacterial flora of the intestine in patients with Crohn's disease and in a control group.

The bacterial flora intimately associated with the intestinal mucosa of patients with Crohn's disease has been examined and compared with the mucosal flora of a control group. Specimens were obtained at operation from patients undergoing intestinal surgery. Whole thickness intestinal sections were taken from the diseased segment and from a portion of uninvolved intestine from patients with Crohn's disease as well as from a control group. A section of each specimen was examined histologically. Twenty-two specimens of Crohn's tissue (12 ileum, 10 colon) and 46 control samples from small and large bowel were examined using strictly anaerobic bacteriological techniques in an anaerobic chamber. Organisms were grown under both aerobic and anaerobic conditions. A mucosal flora was found to exist in all the large bowel samples and in three-quarters of the small bowel samples. It was qualitatively similar in all the samples, consisting mainly of Gram positive bacteria, aerobic Gram negative rods and bacteroides. Greater numbers of bacteria were associated with colonic tissue (10(7) - 10(8) per g) than with tissue from the jejunum (10(3) - 10(4) per g). This difference was statistically significant (p<0.03). Samples from the terminal ileum were quantitatively intermediate between jejunum and colon. There was no statistical difference in the numbers of bacteria associated with Crohn's tissue compared with histologically normal tissue from the same patients and from the control group of patients. Among the bacterial isolates, however, Enterobacteria were more commonly associated with Crohn's tissue.

Aerobiosis↗
PubMed1976

Determination of monoamine and monoamine metabolites in the human brain: post mortem studies in a group of suicides and in a control group.

Different nuclei and regions of the brain from patients who had committed suicide and from controls were analysed for their content of monoamine and monoamine metabolites. There was a post mortem breakdown of 5-hydroxyindoleacetic acid (5-HIAA) which could be correlated to the time elapsed between the occurrence of death and autopsy. Homovanillic acid (HVA) and the monoamines did not decrease post mortem during the time observed (6-148 hours). There was no significant correlation between age and chemical variables in this investigation. There were no significant group differences between suicides and controls concerning dopamine, noradrenaline, 5-hydroxytryptamine, and HVA, 5-HIAA levels were significantly lower in the suicide group in six out of eight parts of the brain investigated. It was, however, also demonstrated that there was a longer time elapse between the occurrence of death and autopsy in the suicide group. The suicides came on average 48 hours later to autopsy than the controls. As there was a post mortem decrease of 5-HIAA, this time variable had to be kept constant when group differences were analysed. When the influence of this time variable was eliminated there were no longer any differences between suicides and controls. According to this investigation, there seem to be no differences in levels of monoamines and their metabolites between suicides and controls.

Adult↗
PubMed1978

Is the concept of "control group" valid? A quantitative comparison of behavior of caged baboon groups.

Behavioral comparisons between six caged baboon groups indicate that the groups have consistent and similar behavioral attributes. At the same time it is possible to distinguish between classes of animals in each group such as males versus females and high status versus low status rank. Comparable results are obtained in both ANOVA and Kruskal-Wallis one-way analysis of variance by ranks. This investigation supports the assumption that baboon groups exhibit behaviors that are both consistent and predictable where environment and group composition are controlled. Thus there appears to be a strong species-appropriate set of behaviors. Behavioral plasticity and group variability might be due largely to a combination of environmental stimuli and the particular history of that group. Differential individual histories or idiosyncracies do not invalidate experimental designs which rely on randomization to structure control groups.

Animals↗
PubMed1992

Stroke risk from alcohol consumption using different control groups.

BACKGROUND AND PURPOSE: Our aim in this study was to investigate the relation between chronic alcohol consumption and stroke. METHODS: A case-control study was carried out using two hospital-based control groups and the results of a community-based survey of alcohol consumption. Hospital-based control subjects were chosen either from "general" medical admissions or a subset of "select" admissions that excluded possible alcohol-related admissions. Cases were selected from hospital inpatients. RESULTS: The relative risk for stroke associated with alcohol consumption greater than 300 grams per week for general control subjects was 0.73 (95% confidence interval [CI], 0.54-3.49) compared with 1.30 (95% CI, 0.42-4.05) for select control subjects. The odds ratio was further increased to 1.93 (95% CI, 0.87-4.28) using data from the community-based survey. None of these estimates were statistically significant. CONCLUSIONS: These results illustrate how the risk associated with alcohol consumption varies depending on the choice of control groups and may explain the contradictory results from previous case-control studies. Because of different biases associated with control selection, we believe that the results of this study are consistent with those of other studies that demonstrate a modest increased risk for stroke associated with alcohol consumption.

Adult↗
PubMed1975

Proton magnetic resonance studies of carbonic anhydrase. II. Group controlling catalytic activity.

The seven resonances observed in the histidine region of the proton magnetic resonance (pmr) spectrum of human carbonic anhydrase B and reported in the preceding paper are studied in the presence of sulfonamide, azide, cyanide, and chloride inhibitors and in metal-free, cadmium substituted, cobalt substituted, and carboxymethylated forms of the enzyme. Results indicate that the two resonances that move-downfield with increasing pH and the two that do not move with pH reflect residues located at the active site. The first two resonances are assigned to the same titratable histidine whose pK value of 8.24 corresponds to that of the group controlling catalytic activity. Addition of anions or sulfonamides, removal of zinc, or substitution of cadmium for zinc at the active site, procedures known to abolish enzymatic activity, prevent titration of this residue. Partial inhibition of carbonic anhydrase by chloride slectively increases the pK value of the group controlling catalytic activity and of the histidine with pK equals 8.24. Experiments with metal-free and cadmium carbonic anhydrases and comparisons with model systems suggest that this histidine is bound to the metal ion at high pH; at low pH this complex appears to dissociate as protons compete with the metal for the imidazole group. It is proposed that ionization of the group controlling catalytic activity represents loss of the pyrrole proton of this neutral ligand when it binds to Zn(II), forming an imidazolate anion and juxtaposing a strong base and a powerful Lewis acid at the active site. When bound to zinc as an anion, this histidine can act as a general base catalyst in the hydration of carbon dioxide and be replaced as a metal ligand by an oxygen of the substrate in the course of the reaction. The histidine-metal complex is thought to exist in a strained configuration in the active enzyme so that its imidazole-metal bond is readily broken on addition of substrates or inhibitors. This model is consistent with the available data on the enzyme and is discussed in relation to alternative proposals.

Acetazolamide↗
PubMed1977

[Statistical analysis of non-uniform data obtained in several experiments with unequal experimental and control groups].

The author suggests a method of calculation of mathematically unbiased difference between the means of combined experimental and control groups and their calculated statistica-significance. Non-uniformity in the results of measurements between individual experiments is admissible. The coefficients adjusting the number of observations in the experimental and control groups to each experiment separately were found by minimizing the square of the mean error of the mentioned difference. Experimental results were united after the correction by means of the coefficients found.

Adjuvants, Immunologic↗
PubMed1976

Issues at the clinical-research interface: placebo effect control groups.

At the clinical-research interface, controls are a significant issue in group therapy evaluation. The authors describe and analyze their unique experience with placebo effect control groups conducted prior to brief, group psychotherapy for married couples. Procedures are outlined and participant reactions noted. Solicited ratings and spontaneous comments provide assessment data. The evidence suggests the feasibility of placebo effect control groups in the context studied. Proposed methodological refinements and clinical implications may be useful for future research efforts.

Adult↗
PubMed1992

Conditioned tolerance to morphine hypoalgesia: compensatory hyperalgesia in the experimental group or conditioned hypoalgesia in the control group?

Five experiments used rats to examine the role of noxious stimulation in the development of contextually controlled morphine hypoalgesic tolerance and in the mediation of this tolerance by an associated hyperalgesic response. There was evidence for contextually controlled tolerance to morphine's hypoalgesic effects and an associated hyperalgesic response in rats injected with morphine and trained with noxious stimulation, but not in rats repeatedly exposed to morphine in the absence of that stimulation (Experiments 1 and 5). Latent inhibition (Experiment 2) and extinction (Experiment 3) of tolerance also depended upon pairing drug-related cues with noxious stimulation. The level of sensitivity-reactivity to noxious stimulation in morphine-tolerant rats tested with the drug was related to the intensity of the noxious stimulation that had been paired with the test context (Experiment 4). The results were interpreted to mean that some of the evidence for a Pavlovian involvement in tolerance development can be explained in terms of morphine's interference with the acquisition, but not with the expression of the hypoalgesic response otherwise acquired by cues paired with noxious stimulation.

Animals↗
PubMed1978

Psychiatric evaluation of youth with cleft lip-palate matched with a control group.

Ten subjects were randomly selected from each of four pools of patients (male CPO, male CLP, female CPO and CLP) age six to 18 years regularly followed by a cleft palate clinic. Forty controls from a family practice clinic were matched for age, sex, and socio-economic status. Congenital second anomalies were present in 13 cleft children, five of whom were male CPO. Significant hearing loss was found in 11 cleft children and speech articulation problems in about 50 per cent of the sample. Both cleft and control groups were interviewed by a child psychiatrist, and mothers completed a behavior rating check list. There were no significant differences in the number of subjects from both groups having psychiatric diagnoses or conflicts. Mother's ratings indicated that cleft group had significantly more subjects with excessive dependency problems while control group had significantly more subjects having problems with resenting correction, talking negatively about self, and projecting blame to others. Significantly more male CPO and female CLP patients had psychiatric diagnoses, particularly mental retardation and developmental deviations, when compared to male CLP and female CPO groups. Cleft children with articulation problems were more likely to have psychiatric diagnoses and conflicts.

Abnormalities, Multiple↗