SEARCH · Search PubMed

Results for “Sampling Errors”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources

PubMed1977

Staging laparotomy with splenectomy in Hodgkin's disease.

The series includes 91 patients with Hodgkin's disease who underwent a staging laparotomy with splenectomy during the years 1971-1976, in 82% of them as part of the initial evaluation before therapy. Positive abdominal lymph nodes were found in 29% of the patients, a positive spleen in 37%, and a positive liver in 10%. Follow-up of patients who lacked abdominal involvement at laparotomy indicate that sampling error was only of marginal importance. Evaluation of the therapeutic implications of the operation indicated that 41% of the patients benefited from the procedure; 31% by changing stage and 10% by changing radiation therapy port. Five patients had minor surgical complications. The mortality rate was nil.

Abdominal Neoplasms↗

PubMed1977

[Metameters for the statistical treatment of data expressed in percentage values].

Medical or biochemical data are often expressed as percentages or proportions. Since the sampling error of percentage values does not usually follow a normal (Laplace-Gauss) model, statistical significance tests may give unsatisfactory results, when applied to the original data; however, the fitting to a normal distribution can be improved by choosing suitable metameters. The Author proposes the transformation of percentages to a hyperbolic function zp, based on Fisher's z, which is almost normally distributed. The performances of this transformation are checked, with special reference to medical laboratory problems.

Biochemical Phenomena↗

PubMed1977

Realtion of heart rate control to heartbeat perception.

The relation of heartbeat perception to voluntary control of heart rate (HR) and to learning of enhanced HR control during feedback was studied in three experiments. In Experiment I heartbeat perception was unrelated to voluntary control of HR but was negatively correlated with HR learning. Experiments II and III showed that heartbeat perception was unrelated to either initial voluntary control or learning and suggested that sampling error accounted for the negative correlation in Experiment I. Experiment I also demonstrated that learned increases in HR are retained for at least 10 weeks following feedback training. Autonomic Perception Questionnaire scores were not predictive of voluntary HR control or learning.

Adolescent↗

PubMed1981

Prenatal detection of neural tube defects by maternal serum alphafetoprotein assay.

Mass screening for fetal neural tube defects using maternal serum alpha-fetoprotein assay as the initial test is financially justified in South Africa, despite the relatively low incidence of these defects in this country, using enzyme-linked immunosorbent assay. This technique is efficient and inexpensive and lends itself to mass screening. We report a pilot study in which 3153 maternal serum samples were received during a 4-month period. Of these 3102 were assayed and the outcome of pregnancy was recorded in 2069 cases. On the first assay 147 (4.7%) of the women had serum alpha-fetoprotein levels which were high for the gestational dates given, but in retrospect about half of these had been misinterpreted because of incorrect dates. Among the remainder, 6 women proved to be carrying twins, 4 aborted spontaneously, 10 delivered prematurely or had infants with intra-uterine growth retardation, and 4 had a fetus with a neural tube defect. Two affected fetuses were missed by screening, in both cases because serum was taken after 20 weeks gestation. In this sample the incidence in Indians (1/1000)and Coloureds (1/600) was as expected, but in Whites it was much higher (1/130), which probably reflects a sampling error and indicates that the epidemiology of neural tube defects in South Africa requires investigation.

Adolescent↗

PubMed1983

Language-related skills in children with acute lymphocytic leukemia.

The success of cranial irradiation and chemotherapy in the treatment of acute lymphocytic leukemia (ALL) has raised concerns about possible central nervous system damage in long-term survivors. The current study focused on language-related skill measures obtained as part of a neuropsychological test battery. Performance was analyzed as a function of age at diagnosis and age at evaluation in a sample of 110 children with ALL (mean age = 13.28 years). Results, although for the most part nonsignificant, do reveal significantly poorer performance on an Aphasia Screening Test rating by those diagnosed early (at or before five years of age) and assessed at or before 13 years of age when contrasted with those diagnosed early and assessed after their thirteenth year. Further analysis revealed a significant decline in spelling scores for those off therapy for more than two years. There was also a consistent trend for decline across most language-related skills measures as time off therapy increased. These results reflect either recovery from mild acute language dysfunction over time superimposed on a general trend for decline in language-related skills as time off therapy increases, or sampling error. Suggestions for future lines of investigation are discussed.

Achievement↗

PubMed1982

Human papillomavirus. Frequency and distribution in plantar and common warts.

Fifty-nine (24 plantar, 35 common) warts surgically excised from 44 patients (15 female, 29 male), 18 to 32 years old, were examined by electron microscopy (EM) for papillomavirus particles and by fluorescent antibody (FA) and peroxidase-antiperoxidase (PAP) tests for human papillomavirus type 1 (HPV-1)-specific antigens and papillomavirus genus-specific (common) antigens. Fifty per cent of plantar warts and 52 per cent of common warts were positive for HPV by EM. When examined by FA and PAP for genus-specific antigens, 58 per cent of plantar warts and 68 per cent of common warts were positive. Fifty per cent of plantar warts and 11 per cent of common warts were caused by HPV-1 as determined by reactivity with HPV-1 type-specific antiserum. All warts positive by EM were positive by FA and PAP. Sampling error accounted for warts positive by FA and PAP but not by EM. Forty-two per cent of plantar warts and 31 per cent of common warts were negative by both EM and FA and PAP. The warts caused by HPV-1 contained more virus and were more clinically aggressive than warts caused by other HPV. This study shows that the results obtained by the PAP technique using papillomavirus genus- and type-specific antisera on formalin-fixed, paraffin-embedded tissue available to the diagnostic pathologist are concordant with the results obtained by methodology usually available only to the experimental pathologist.

Adolescent↗

PubMedDate not supplied

Accuracy of cytologic diagnosis of central nervous system neoplasms in sterotactic biopsies.

The cytohistologic correlation is reported for 112 of the 128 consecutive sterotactic aspiration biopsies performed on patients with clinical and neuroradiologic evidence of brain tumors investigated at the Neurosurgery Department, Karolinska Hospital, from 1976 to 1979. The cytodiagnostic accuracy of benign and malignant tumors was 87% when adequate cell material was obtained. In 17 benign tumors of the sellar region, the diagnostic rate was 88%; cytologic examination independent of histologic biopsy is feasible in this area. The cytodiagnostic accuracy for 95 malignant central nervous system (CNS) tumors was 87% after adjusting for the appreciable sampling error inherent in the use of a stereotactic procedure during the early phase of the study. Two histopathologically proven infectious lesions were reported cytologically as benign. The main microscopic problems were the recognition of highly differentiated astroglial neoplasms and the differential diagnosis between poorly differentiated brain neoplasms and metastases to the CNS. Cytodiagnostic accuracy of CNS tumors can be increased by technical improvements in the stereotactic device, diagnostic experience and immunochemical staining.

Biopsy, Needle↗

PubMed1983

Sampling variability of liver biopsy in inflammatory bowel disease.

Sampling errors may occur when hepatic needle biopsy specimens are obtained for histologic examination. We obtained biopsy specimens from the right and left lobes of the livers of 29 patients who were to undergo surgery for inflammatory bowel disease. The histologic appearances of Kupffer's cell hyperplasia, fatty change, portal tract inflammation, and focal necrosis, but not giant cell granulomas, were well represented by a single specimen. The incidence of minor hepatic abnormalities was high and is likely to reflect the severity of the disease leading to surgery, but serious lesions were uncommon.

Biopsy, Needle↗

PubMed1984

The role of the biopsy in diagnosis of early gastric cancer.

In order to determine the reliability of endoscopic biopsy in diagnosis of early gastric cancer, and to clarify the problems with biopsies, preoperative endoscopic biopsies from 771 early gastric cancer cases were reviewed and analyzed clinicopathologically in comparison with surgically resected specimens. The 771 cancers were surgically resected at the National Cancer Center Hospital during the period from 1972 to 1982. Definite histological diagnosis was obtained in 87.4% of the carcinomas at the initial biopsies. Repeated biopsy raised the percentage of correct definite diagnoses to 96.1%. False-negative (including suspicion of cancer) diagnosis was most frequent in the case of depressed lesions (50 lesions). Half of the false negatives were found to be due to sampling errors by the endoscopists. The other half of these 50 lesions were diagnosed as "suspicious of malignancy" because of the histological difficulty in differentiating early gastric cancer from regenerative atypia with intestinal metaplasia, or because there was not enough information, or for the other reasons. Most of the 31 false-negative diagnoses at the initial biopsy from elevated lesions were reported as adenoma (group III) or suspicious of carcinoma (group IV), indicating that differential diagnosis between well-differentiated adenocarcinoma and adenoma is very difficult. The result of the present study suggests that repeated biopsy from correct sites and discussion of the lesions between clinicians and pathologists are very important.

Biopsy↗

PubMed1984

A tableted enzymic reagent for salicylate, for use in a discrete multiwavelength analytical system (Paramax).

A fully enzymic reagent for determination of salicylate in serum has been developed for use in the Paramax analytical system. The assay, run as an equilibrium determination, is based on the reaction of salicylate with NADPH and oxygen in the presence of salicylate hydroxylase (EC 1.14.13.1) to form catechol, NADP+, carbon dioxide, and water. The reaction is complete within 7 min, after which time the resulting absorbance change at 340/405 nm is measured. The sample:reagent ratio is 1:60 (5 microL of sample in a 300 microL final reaction volume). A single 30-mg tablet contains all of the reactants with tableting excipients. The use of NADPH eliminates interferences from reactions involving NADH. The large sample:reagent ratio, high sensitivity, and choice of bichromatic wavelengths minimize sample error. Results are linearly related to salicylate concentration to 1500 mg/L. Precision (CV) is 1.7% at 540 mg/L and 2.4% at 280 mg/L.

Autoanalysis↗

PubMed1980

Electron microscopy in the diagnosis of neuroblastoma.

I review the accumulated knowledge regarding the electron microscopy of neuroblastic tumors using a retrospective study of 13 primarily small cell neoplasms for which the diagnosis of a neuroblastic tumor (neuroblastoma, ganglioneuroblastoma, ganglioneuroma) was either considered or eventually established. A fine fibrillary background, even if focally distributed by light microscopy and seemingly not recovered in the thick sections, correlated with the presence ultrastructurally of neuritic processes bearing dense core ("neurosecretory") granules and lucent vesicles. In three cases without any fibrillary background by light microscopy, granule-bearing processes were not found by electron microscopy, and different diagnoses were subsequently established for two of those cases. From the standpoint of diagnosis, the sampling error normally introduced in ultrastructural examinations has not been reported to be a significant problem, nor was it in the present cases. Therefore, in supporting a light microscopic diagnosis of neuroblastoma, neuritic processes containing dense granules with or without lucent vesicles should be documented. Neuroblastic tumors with evidence of maturity, ie, ganglion cell differentiation, had the best developed morphologic features by both forms of microscopy. Schwann cells were observed in four cases, including one neuroblastoma. The presence of these cells by electron microscopy, although absent by light microscopy, may reflect an early phase of tumor maturation.

Adolescent↗

PubMed1981

Tobacco, alcohol, asbestos, and nickel in the etiology of cancer of the larynx: a case-control study.

A case-control study of laryngeal cancer was conducted in southern Ontario between 1977 and 1979 with 204 subjects with newly diagnosed cancer and 204 controls, individually matched by sex, age, and residence. Tobacco products and alcohol showed strong associations with cancer of the larynx for males, with relative risks (RR) for users of cigarettes, cigars or cigarillos, pipes, and alcohol of 6.1, 2.9, 1.6, and 5.2, respectively. The population attributable risk percent for males using tobacco products and alcohol together was estimated to be 94%. Cigarette smoking was also an important risk factor for females, although the small number of female pairs (20) precluded any meaningful detailed analysis of other possible risk factors. The RR for males for exposure to asbestos after the effects of cigarette smoking were controlled was 2.3, and the effects seemed restricted to cigarette smokers. The findings on asbestos were based on small numbers of cases and controls exposed and consequently were subject to large sampling errors. The estimate was consistent, however, with that from other studies and supported a causal role for asbestos exposure and cancer of the larynx. The RR for males for exposure to nickel was 0.9.

Asbestos↗

PubMed1982

Single-photon emission tomography with a 12-pinhole collimator.

To assess the advantages of more complete angular sampling and of more views in the tomographic reconstruction process, tomographic imaging with a 12-pinhole (12PH) collimator has been compared with 7-pinhole tomography (7PH). The 12PH system gives a 50% increase in sensitivity but resolution degrades more rapidly with depth. The 7PH and 12PH systems provide similar accuracy of detection of lesions in a myocardial ring phantom. The 7PH images, however, demonstrated more noise and "ripple" artifacts. The 12PH system offers a larger reconstruction volume and generates fewer artifacts when the collimator is misaligned with the myocardial long-axis, thus making patient positioning less critical than with 7PH. A disadvantage is that individual views are minified by the 12PH collimator, and a 256 X 256 image matrix should be used during image acquisition to limit digital sampling errors.

Evaluation Studies as Topic↗

PubMed1982

False-negative cytology rates in patients in whom invasive cervical cancer subsequently developed.

The 3-year screening interval recommended by the American Cancer Society would appear to decrease the detection of premalignant and malignant disease. The authors have shown that 20% of study patients in whom subsequently invasive cervical cancer developed had at least 2 negative Papanicolaou smears within 3 years of the diagnosis of cancer. Moreover, the majority of false-negative results in the series could be attributed to sample error. The authors recommend yearly or at least biennial cervical cytologic screening.

Adult↗

PubMedDate not supplied

Evaluation of methods for measurement of steroid hormone receptors.

Several factors affecting estrogen receptor assays have been investigated. Pools of rabbit uterus cytosol and human tumor cytosol were utilized to minimize sampling error. Optimum concentration of diethylstilbestrol was found to be 1000 times the highest labeled ligand concentration. Dithiothreitol (DTT) and ionic strength had no effect on receptor value in human tumor cytosols. Optimum pH for estrogen receptor assay is 7.78.

Animals↗

PubMed1981

National survey of hospital pharmacy technician use.

Results of a national survey of nonfederal hospitals on the use of pharmacy technicians are presented. A random sample of nonfederal hospitals in the U.S. that employ a pharmacist (either full- or part-time) was selected; the sample size was 808. Survey questionnaires were mailed to directors of pharmacy at those hospitals. The response rate was 83.4%. Survey results are reported as percent of total respondents +/- three sampling errors. Overall, 75.4 +/- 5.8% of hospitals use pharmacy technicians; more larger hospitals use technicians than do smaller ones. The most common reason for not using pharmacy technicians was insufficient workload. For all hospitals, 43.8 +/- 7.2% do not have enough technicians, usually because of insufficient funds. Pharmacy directors preferred that technicians be trained in formal program (51.7 +/- 5.4%), and most preferred training (either formal or on-the-job) be conducted in-house (60.2 +/- 4.5%). Respondents were overall slightly favorable toward both accreditation of technician-training programs and certification of individual technicians, but only a small group had no opinion--large groups of respondents had either positive or negative feelings on the issues. Data collected on approximately 2600 technicians at the respondents' hospitals showed that most technicians were high school graduates who have been working as a technician about two years and were trained informally on-the-job.

Pharmacy Service, Hospital↗

PubMed1980

Histology in chronic hepatitis.

The subdivision of chronic hepatitis into chronic persistent hepatitis (CPH) and chronic active hepatitis (CAH) remains the basis for diagnosis, but requires modification and amplification. Mild CAH closely resembles CPH, and corticosteroids may suppress CAH to a picture of CPH. Sampling error may explain some examples of apparent transition from CPH to CAH. The lesion of CPH is non-specific, and other causes of portal inflammation must be excluded. Definition of CAH must incorporate bridging hepatic necrosis (BHN) which speeds development of cirrhosis. Portal/periportal inflammation and necrosis in acute hepatitis remain important predictors of chronicity. CAH varies widely in severity and pathology. Lobular activity may be important in prognosis; when found alone, it constitutes a third type of chronic hepatitis, chronic lobular hepatitis. Chronic hepatitis can be re-classified in a practical way which crosses conventional categories.

Chronic Disease↗

PubMed1994

Radiation therapy for local recurrence of prostate cancer after radical prostatectomy.

A definitive conclusion about the value of ART is not possible from the data available: Both the methods of radiation therapy and the techniques in the diagnosis of locally persistent disease have evolved over the years. Currently, the data lead to the conclusion that ART decreases local recurrence but does not improve overall survival. Yet the PSA data strongly suggest that only locally persistent disease is a common event after radical prostatectomy (particularly in margin-positive disease only) and that current ART techniques are inadequate in many but not all of these patients. Certainly some men seem to have their local disease eliminated by ART to remain NED, but it is unclear exactly how to select them. Many experts also believe that keeping the PSA as low as possible for as long as possible, with sequential applications of ART and then androgen ablation as necessary, is a good emotional if not medical strategy. For example, all patients now wish to know their PSA level and worry about it. Also, potency can be maintained or regained after ART but becomes improbable after androgen ablation because of loss of libido. Clearly, a study randomizing high-risk postoperative patients into observation versus ART is needed and indeed such a study is under way in the Southwestern and Eastern Cooperative oncology groups, but to date accrual is inadequate (Ian Thompson, Jr, MD, personal communication, May 1994). This study must be supported. When participation in the randomized study is not possible, we believe four tentative recommendations about the application of ART can be made based on the available data (Fig. 1): (1) For high-risk patients (e.g., high Gleason score and/or high pathologic stage) with initially undetectable PSA levels, we recommend instituting ART before any rise in postoperative PSA levels because low-volume disease may best respond to this therapy. (2) For patients with rapidly rising or initially detectable postoperative PSA levels (especially if NBA is negative), we believe that the disease has most likely already spread to distant sites and would initiate therapy aimed at systemic disease. (3) For those patients with rapidly rising postoperative PSA but with positive NBA, we recommend local irradiation. (4) if the postoperative PSAlevels rise gradually, we would initiate ART regardless of the needle biopsy result because of the possibility of NBA sampling error and the fact that the gradual increase in PSA suggests that the disease is still local.(ABSTRACT TRUNCATED AT 400 WORDS)

Follow-Up Studies↗