Analysis of variance (ANOVA) is one of the most frequently used statistical methods in medical research. The need for ANOVA arises from the error of alpha level inflation, which increases Type 1 error probability (false positive) and is caused by multiple comparisons. ANOVA uses the statistic F, which is the ratio of between and within group variances. The main interest of analysis is focused on the differences of group means; however, ANOVA focuses on the difference of variances. The illustrated figures would serve as a suitable guide to understand how ANOVA determines the mean difference problems by using between and within group variance differences.
Analysis of Variance* ; False Positive Reactions ; Inflation, Economic

Frozen section diagnosis is a highly useful method of diagnosis. There were 4434 frozen sections, 24 false positive diagnosis, 65 false negative diagnosis and 30 deferred diagnosis. This method achieves the highest accuracy when there is a cooperation between experienced surgeon and reliable and careful pathologist. It is wise to defer the diagnosis of consult to other pathologist in difficult situation.
Biopsy/*standards ; False Negative Reactions ; False Positive Reactions ; *Frozen Sections ; Humans ; *Microtomy ; Neoplasms/*diagnosis/pathology ; *Predictive Value of Tests

BACKGROUND: The dipstick methodology is the most fundamental urinalysis but interfered by many factors. We evaluated the effect of semen contamination on the urine dipsticks. METHODS: Thirty-two specimens for semen analysis were enrolled. After semen was directly applied on urine dipsticks, residual samples were diluted in pooled normal urine. Urine dipsticks were performed at each dilution titer. Seminal plasma separated by centrifugation of semen were also tested in the same manner. RESULTS: All semen showed positive results for blood, protein and leukocytes. The intensities of reaction for blood and leukocytes were correlated with sperm concentration. The negative conversion of blood and protein occurred at 1:100, and that of leukocytes occurred at 1:50. Seminal plasma showed nearly the same findings. CONCLUSIONS: Semen contamination of urine may cause false positive reaction especially for blood and protein on the urine dipsticks. It should therefore be considered when assessing unexplained, transient hematuria or proteinuria.
Centrifugation ; False Positive Reactions ; Hematuria ; Leukocytes ; Proteinuria ; Semen Analysis ; Semen* ; Spermatozoa ; Urinalysis

Duodenal leiomyomas are rare benign tumors of mesenchymal origin. Generally, Fluorodeoxyglucose (FDG)-PET would have a negative finding in leiomyomas. A 52-year-old man was referred to our hospital with melena. Gastroendoscopy revealed the presence of a huge submucosal tumor with ulceration at the duodenum bulb. Subsequent CT demonstrated a poorly enhanced oval mass adjoining the duodenal bulb. FDG-PET scan demonstrated an excessive accumulation of FDG in the lesion. A definitive diagnosis of duodenal leiomyoma was made on the basis of the pathologic finding of his surgical specimen. We report in this first case that duodenal leiomyma may show a potential pitfall of giving a positive FDG-PET result. Through this case, we would like to caution clinicians against PET-dependent evaluations of malignant potential of duodenal submucosal tumors.
Duodenum ; False Positive Reactions ; Fluorodeoxyglucose F18 ; Humans ; Leiomyoma ; Melena ; Middle Aged ; Positron-Emission Tomography ; Ulcer

BACKGROUND: We evaluated the performance and false positive rate of Mediace RPR test (Sekisui, Japan), a newly introduced nontreponemal test using a chemistry autoanalyzer. METHODS: The sensitivity of Mediace RPR test was analyzed using sera from 50 patients with syphilis in different stages (8 primary, 7 secondary, and 35 latent), 14 sera positive with fluorescent treponemal antibody absorption (FTA-ABS) IgM, and 74 sera positive with conventional rapid plasma regain (RPR) card test (Asan, Korea) and also positive with Treponema pallidum hemagglutination (TPHA) test or FTA-ABS IgG test. The specificity was analyzed on 108 healthy blood donors. We also performed RPR card test on 302 sera that had been tested positive with Mediace RPR test and also performed TPHA or FTA-ABS IgG test to analyze the false positive rate of Mediace RPR test. A cutoff value of 0.5 R.U. (RPR unit) was used for Mediace RPR test. RESULTS: Mediace RPR test on syphilitic sera of different stages (primary, secondary, and latent stages) and FTA-ABS IgM positive sera showed a sensitivity of 100%, 100%, 82.9% and 100%, respectively. Among the 74 sera positive with conventional RPR card test and TPHA or FTA-ABS IgG test, 55 were positive with Mediace test. The specificity of Mediace RPR test on blood donors was 97.2%. Among the 302 sera positive with Mediace RPR test, 137 sera (45.4%) were negative by RPR card and TPHA/FTA-ABS IgG tests. CONCLUSIONS: Although the sensitivities of Mediace RPR were good for primary and secondary syphilis, due to its high negative rate of Mediace RPR over the conventional RPR positive samples, further studies are necessary whether it can replace conventional nontreponemal test for screening purpose. Moreover, in view of the high false positive rate, positive results by Mediace RPR test should be confirmed with treponemal tests.
Autoanalysis/methods ; False Positive Reactions ; Humans ; ROC Curve ; Sensitivity and Specificity ; Syphilis/*diagnosis ; Syphilis Serodiagnosis/*methods

Immunohistochemical study with carcinoembryonic antigen (CEA) by peroxidase-antiperoxidase (PAP) method in rat bladder tumor induced by administration of N-butyl-N-( 4-hydroxybutyl)- nitrosamine was performed to know the immunological cross reactivity between human bladder tumor and experimentally induced rat bladder tumor and to evaluate, if all, its role as an indicator of malignant potential in rat bladder tumor. The results revealed 6 false positive reactions regardless of their histologic types and gave us no meaningful informations about ongoing disease process.
Animals ; Carcinoembryonic Antigen* ; False Positive Reactions ; Humans ; Rats ; Urinary Bladder Neoplasms* ; Urinary Bladder*

OBJECTIVE: The purpose of this study was to develop a new method for automated mass detection in digital mammographic images using templates. MATERIALS AND METHODS: Masses were detected using a two steps process. First, the pixels in the mammogram images were scanned in 8 directions, and regions of interest (ROI) were identified using various thresholds. Then, a mass template was used to categorize the ROI as true masses or non-masses based on their morphologies. Each pixel of a ROI was scanned with a mass template to determine whether there was a shape (part of a ROI) similar to the mass in the template. The similarity was controlled using two thresholds. If a shape was detected, then the coordinates of the shape were recorded as part of a true mass. To test the system's efficiency, we applied this process to 52 mammogram images from the Mammographic Image Analysis Society (MIAS) database. RESULTS: Three hundred and thirty-two ROI were identified using the ROI specification methods. These ROI were classified using three templates whose diameters were 10, 20 and 30 pixels. The results of this experiment showed that using the templates with these diameters achieved sensitivities of 93%, 90% and 81% with 1.3, 0.7 and 0.33 false positives per image respectively. CONCLUSION: These results indicate that the detection performance of this template based algorithm is satisfactory, and may improve the performance of computer-aided analysis of mammographic images and early diagnosis of mammographic masses.
Sensitivity and Specificity ; Radiographic Image Enhancement ; Mammography/*methods ; Humans ; False Positive Reactions ; Automation ; Algorithms

We messured delayed cutaneous hypersensitivity reactions by Multitest CMI Kit. Total 209 normal adults ranging in age from 17 to 55 year(male 106, female 103) were tested. The results were obtained as follows ; 1. Sum of average diameter of positive antigens wss 20.7mm in male and 15.6mm in female. 2. Number of positive antigens was 3.9 in male and 3.4 in female. 3. Rate of anergy was 1.4%(0.9% in male, 1.9% in female). 4. The rate of subjects below warning score(below 10mm in male, below 5mm in female) was 2.8% in male and 5.8% in female. 5. Antigen with the highest response was tuberculin in both sex(male 95.3%, female 89.3%) and antigen with the lowest response was trichophyton(22.5%). 6. Aversge score of positive response of every antigens was highest in tuberculin at both sex(male 2.8mm, female 2,6mm) 7. Average score of total antigens with positive response was 5.5mm in male and 4.6mm in female. 8. The rate of false positive reaction to 70% W/V glycerine was 1.4% totally.
Adult* ; False Positive Reactions ; Female ; Glycerol ; Humans ; Hypersensitivity* ; Korea* ; Male ; Tuberculin

OBJECTIVETo explore the impact of misclassification in binary explanatory variables on the effects associated with 'exposure-disease'.

METHODSBased upon the functions of probabilities on misclassification, effects of association and proportions of exposure, the 'R Project for Statistical Computing' method was used to analyze the impact of misclassification on the validity of a study.

RESULTSTo the linear model case, the effect of nondifferential misclassification serves as an attenuating bias. When r = 0.5, the bias is symmetric in both sensitivity and specificity but when r is not equal to 0.5, the bias is not symmetric in sensitivity and specificity. When misclassification is nondifferential, estimated odds ratio tends to be 1 while the exposure prevalence in the control tends to be 0 or 1. Bias seems to be very complex in differential misclassification than in nondifferential misclassification that can make OR tend to or be away from the null value.

CONCLUSIONThe impact of exposure misclassification on the effect associated with exposure--disease is complicated, hence necessary to understand, to control, and to assess bias of misclassification in order to correctly interpret the results of a study.

BACKGROUND: Immuno-PCR has been known as a highly sensitive and specific method, yet no standardized protocol is available. We analyzed each step of immuno-PCR to develop a reliable standardized method. METHODS: We made a protocol modified from several methods reported previously, and performed immuno-PCR, but false positive reactions were noted. To reduce the false positivity, we investigated the buffer reagents and biotin-labelled oligo-nucleotide probe. Using a finally determined protocol, we compared the detection-limits of the immuno-PCR and ELISA methods. RESULTS: Streptavidin was identified as a main reagent causing a non-specific binding, thus it was replaced by neutravidin. The employment of CAS block as a dilution buffer for the biotin-labelled oligo-nucleotide probe and Casein block as a buffer for the detection antibodies resulted in a dramatic reduction in the false positive reactions. The standardized immuno-PCR detected angiogenin antigen at a concentration as low as 5 fg/mL, while an ELISA method detected 5 pg/mL. CONCLUSIONS: The immuno-PCR procedure newly described in this study was ultra-sensitive with no false positivity. This method can be utilized as an epochal tool for detection of a small amount of antigen which would not be discovered by ELISA method.
Antibodies ; Caseins ; Employment ; Enzyme-Linked Immunosorbent Assay ; False Positive Reactions ; Indicators and Reagents ; Limit of Detection ; Streptavidin