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Results for “Repeatability and Reproducibility”

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PubMed1998

A simplified assay for screening of drug resistance of cell-associated cytomegalovirus strains.

BACKGROUND: Conventional phenotypic drug resistance determination of cell-free clinical human cytomegalovirus (HCMV) isolates is usually very laborious and may take 8-12 weeks, since serially passages of slowly growing viral isolates in tissue cultures are required to obtain a sufficient viral titer for an appropriate inoculum. Rapid screening of a large number of samples would therefore only be possible if simplified, less work-intensive methods are employed. OBJECTIVE: The aim of this work was to develop an assay which speeds up the whole procedure of phenotypic drug resistance determination. Steps of the classical plaque reduction assay should be simplified or omitted, but on the other hand, the assay should be reliable and reproducible. STUDY DESIGN: Twenty-six clinical HCMV isolates from 20 immunocompromised patients (ten pre-treatment and 16 post-treatment with ganciclovir) were tested for drug susceptibility with the simplified plaque reduction assay. Most isolates were tested at least twice in independent assays. Virus titration could be avoided by using four different doses of cell-associated virus from the secondary culture for coculture susceptibility testing. Drug susceptibility values were determined by plaque titration and Probit analysis. RESULTS: All clinical HCMV isolates tested showed a mean ganciclovir ID50 value of 1.98 microM, (range 0.2-12.2; median 0.95) and a mean foscarnet ID50 value of 92.4 microM (range 35.7-181; median 81). All except one isolate were classified ganciclovir sensitive when compared to ID50 values of two ganciclovir resistant control stains (53.7 +/- 6.4 and 12.7 +/- 0.9 microM) and the sensitive laboratory strain Towne (2.1 +/- 0.8 microM). Repeated tests of individual isolates were reproducible, although the infectivity of the inoculum has not been determined prior of the assay. The mean time which elapsed between receipt of the clinical specimen and read-out of the assay was circa 4 weeks. CONCLUSIONS: Phenotypic resistance testing of HCMV isolates following to this protocol drastically reduces expenditure of time and work. The assay allows reliably the discrimination of HCMV isolates as drug resistant or sensitive according to the recent classification criteria of the AIDS Clinical Trials Group (ACTG). The simple handling and uncomplicated calibration of this assay facilitates the screening of large specimen numbers and renders drug susceptibility determination of HCMV more accessible to diagnostic routine use.

Antiviral Agents↗

PubMed2003

Reliability of digital radiography of interproximal dental caries.

PURPOSE: To compare the effects of different image processing modes (filters) on the reproducibility and validity of the assessment of interproximal carious lesions viewed in digitized radiographic images. MATERIALS AND METHODS: Variables studied were film type, exposure time, and tissue scatter radiation. Images were assessed in relation to film type, exposure time and tissue scatter. Standardized radiographs of 50 extracted teeth were obtained and 44 areas of interproximal caries were detected. Six radiographs were obtained of each tooth and digitized using FRIACOM software. Four were made using D-type film with and without soft tissue scatter equivalent at normal exposure time (0.32 seconds) and underexposed (0.16 seconds). Two were made using E-type film with TSE normal (0.16 seconds) and underexposed (0.08 seconds). On each of the 300 radiographs, the central depth (CD) of each carious lesion was measured at 18x magnification both on the unchanged radiographic image and after use of two different filters. All measurements were repeated after 1 week to estimate reproducibility. RESULTS: Histometric CD assessments provided a gold standard for comparison with the radiographic measurements (validity). Whereas reproducibility was not influenced by one of the filters, filter "structure" improved the overall validity of CD measurements. In this study, digital manipulations of radiographic images resulted in statistically significant improvement of the validity of CD measurements.

Dental Caries↗

PubMed2005

Repeated fine-needle aspiration of the thyroid in benign nodular thyroid disease: critical evaluation of long-term follow-up.

UNLABELLED: Fine-needle aspiration (FNA) is the most effective diagnostic means in the management of nodular thyroid disease. Therefore, we decided to evaluate the diagnostic reproducibility of FNA and the usefulness of repeated FNA in benign nodular thyroid disease. We evaluated 799 satisfactory aspirations performed in 306 patients (298 females) aged 14-84 years, followed for 2-12 years. FNAs were performed on an annual basis. Of all patients, 299 (97.71%) maintained benignity: 230 (75.16%) repeated the same cytologic pattern, and 69 (22.54%) showed diagnostic variations within benign pathologies. In 3 patients (0.98%) the diagnosis changed to suspicious and in 4 (1.30%) to papillary carcinoma in the whole group. Of these 4 cases, 1 was diagnosed in the second (0.57%) and 3 in the third repeat FNA (2.25%). In 6 cases in which increased nodular size was observed, no change to malignancy was detected, while 3 of the carcinomas found showed no changes in size. IN CONCLUSION: (1) The variation in cytologic diagnoses within benign pathologies can be attributed to the coexistence of nonuniform pathologies. Aspirations performed in different sites of the nodule would contribute to obtain a more representative specimen. (2) In the absence of suspicious clinical changes and with at least three FNAs confirming the cytologic diagnosis of benignity, the follow-up of nodules by FNA could be discontinued and (3) In our experience, the diagnostic change from benign to malignant after three repeat FNAs appears to indicate that it would be advisable to perform three procedures.

Adolescent↗

PubMed2001

High-performance immunoaffinity chromatography, an immunoaffinity membrane for selective removal of plasma components, and safety evaluation of the latter system.

This article reviews our studies on evaluating the suitability of high-performance immunoaffinity chromatography (HPIAC), an immunoaffinity membrane (IAM) for removing unwanted plasma component, and the safety of the IAM. In an attempt to resolve the problem of amyloid deposition in dialysis patients, we used an HPIAC column, bearing anti-beta 2-microglobulin to remove specifically beta 2-MG from human plasma. The use of a membrane as an affinity ligand support was also studied. A specific antibody immobilized on the membrane was highly effective for the removal of rat immunoglobulin E and of a human serum amyloid P component passed through an extracorporeal circulation (EC) system. Biocompatibility of the specific antibody-bearing IAM was also examined. These techniques should prove useful for medical applications and may have broad applicability to the elimination of any unwanted plasma component. The IAM exerts two functions simultaneously, usual dialysis and elimination by immunoaffinity binding. The rat EC model has been applied as an evaluation system for the safety of medical devices in contact with the blood stream. Combining commonly used hemodialysis (HD) membranes with rat EC, we evaluated the elicitation of immunological responses, as well as the effect of repeated EC. The data suggest that this EC model can reproduce similar immunological responses in HD patients, and can be employed to evaluate medical devices and materials for their delayed, systemic, and repeated exposure effects. The EC system described here can reproduce human HD treatment, remove unwanted substances, and evaluate medical devices and materials for toxicological responses.

Animals↗

PubMedDate not supplied

Comparison of Babcock and ether extraction methods for determination of fat content of milk: collaborative study.

Eleven collaborating laboratories analyzed 18 blind duplicate pairs of raw milk samples for fat by the Babcock method and by a modified Mojonnier ether extraction method in 7 round robins conducted over a 14 month period. Ten laboratories used the Babcock method and 10 used the modified Mojonnier method. Fat content of samples ranged from approximately 2.7 to 5.6%. Mean test value of samples analyzed was approximately 3.9% fat. Average standard deviations of within-laboratory repeatability (Sr) of the Babcock and ether extraction methods were 0.029 and 0.015% fat, respectively. Average standard deviations of between-laboratory reproducibility (SR) of the Babcock and ether extraction methods were 0.039 and 0.020% fat, respectively. Average repeatability relative standard deviations (RSDr) for the Babcock and ether extraction methods were 0.742 and 0.396%; average reproducibility relative standard deviations (RSDR) were 1.014 and 0.512%, respectively. Mean repeatability values (r) and reproducibility values (R) were 0.081 and 0.111% for Babcock and 0.044 and 0.056% for ether extraction, respectively. The ether extraction method demonstrated consistently better within- and between-laboratory agreement. The overall mean test value for the Babcock method was significantly higher (0.021% fat) than that for ether extraction. The difference between Babcock and ether extraction fat test results was different for different farms. In addition, the mean difference between percent fat determined by the Babcock and ether extraction methods was different in different months. There was no correlation in the difference between Babcock and ether extraction methods with the absolute level of fat in the samples in the range of 2.7 to 5.6% fat. The modifications of the AOAC Babcock method and the modified Mojonnier ether extraction method have been approved interim official first action.

Animals↗

PubMed1997

Reproducibility of ultrasound assessment of carotid plaque occurrence, thickness, and morphology. The Tromsø Study.

BACKGROUND AND PURPOSE: Ultrasonography is increasingly used in vascular research, but there is limited information about the reproducibility of the ultrasound method for screening purposes. In this study the reproducibility of ultrasound assessment of carotid plaque occurrence, thickness, and morphology was examined within the setting of a population health survey. METHODS: In 1994/1995, 6720 participants in the Tromsø Study, Norway, underwent B-mode ultrasound scanning of the right carotid artery. The between- and within-sonographer reproducibility of ultrasound assessment of plaque occurrence and thickness was estimated by repeated scanning of a random sample of 107 participants. The between- and within-sonographer reproducibility of plaque morphology classification (echogenicity, four categories and heterogeneity, two categories) was determined by repeated reading of videotaped images of 119 randomly selected arteries with plaques. RESULTS: Between- and within-sonographer agreement on plaque occurrence was substantial with kappa values (95% CI) of 0.72 (0.60 to 0.84) and 0.76 (0.63 to 0.89), respectively. Reproducibility of plaque thickness measurements was moderate, with mean absolute differences ranging between 0.25 and 0.55 mm (coefficients of variation between 13.8% and 22.4%). Agreement on plaque morphology classification was high, with kappa values ranging between 0.54 and 0.73. CONCLUSIONS: Population screening using B-mode ultrasound provides a valuable means for the detection and morphological evaluation of carotid plaques, whereas measurements of plaque thickness are subject to considerable measurement error.

Aged↗

PubMed1997

Comparison of B-mode, M-mode and echo-tracking methods for measurement of the arterial distension waveform.

Measurements of arterial diameter throughout the cardiac cycle (i.e., the arterial distension waveform) are conducted increasingly to study mechanical properties of the arterial wall and changes associated with disease. The distension waveform of peripheral arteries can be measured noninvasively via ultrasonic echo tracking. M-mode imaging, and B-mode imaging. Of these, echo tracking is the most popular method because of its single micrometer resolution during continuous measurements under ideal conditions. However, high resolution within continuous measurements does not imply high reproducibility between measurements. Therefore, we compared repeated measurements of the amplitude of common carotid artery distension in 26 subjects, obtained sequentially in random order by: 1. Off-line echo tracking of digitized radiofrequency ultrasound; 2. M-mode imaging with automated edge detection; and 3. 30-Hz B-mode imaging with automated edge detection and model-based diameter estimation. In each case, the transducer was hand-held and was removed from the neck between repeated measurements. The amplitude of arterial distension was estimated from the serial diameter measurements by maximum likelihood (ML) estimation, by least-squares fit of a Fourier series model, and by application of a cubic smoothing spline. Within continuous measurements, the standard deviation of the ML distension amplitude for neighboring cardiac cycles was significantly smaller (p > 0.05) with echo-tracking (0.023 mm) than with the B-mode (0.036 mm) or M-mode (0.074 mm) methods. However, between discontinuous measurements on the same subject, the standard deviation of the ML distension amplitude was similar for the echo-tracking (0.076 mm) and B-mode (0.073 mm) methods. The Fourier series model and the cubic smoothing spline slightly reduced the standard deviation of the B-mode and M-mode distension amplitudes, but also reduced the mean amplitude estimate. On the basis of this relative comparison of methods, we conclude that, although echo tracking offers high resolution for continuous measurements, the reproducibility of discontinuous measurements of carotid artery distension is no better with echo tracking than can be obtained from 30-Hz B-mode images.

Adult↗

PubMed1993

The significance of probe design in evaluation of colonic perfusion with laser Doppler flowmetry.

The significance of probe design for laser Doppler flowmetry measurement depth and variation was investigated by determining flux versus pressure relations and spatial variability with various probes placed on the serosal surface of porcine sigmoid colon. For two large probes (three optical fibers with diameter and center separation > or = 500 microns) the flux versus pressure relations showed autoregulation, indicating that the mucosal perfusion contributed to the flux signal. The curves were reproducible between individuals. With two smaller probes linear flux versus pressure relations were obtained, indicating a shallow measurement not influenced by the autoregulated mucosal perfusion. The spatial variation expressed as coefficients of variation of repeated recordings at each pressure level was significantly greater with the smaller probes (p < 0.001). For clinical use the larger probes should be preferred. These include all wall layers, and only 3 repeated recordings are needed to obtain a reproducible mean flux value within +/- 10%, as opposed to 10 with the smaller probes.

Animals↗

PubMed1993

Comparison of different methods for the diagnosis of fissure caries without cavitation.

The aim of this study was to compare the accuracy of several common methods for the diagnosis of fissure caries. 63 human teeth without fillings and without any macroscopic carious cavitation but with different degrees of fissure discoloration and decalcification were selected from a pool. Dentists were asked to examine embedded teeth for fissure caries. The examination was done under standard conditions in a professional dental unit. The methods employed were: visual inspection (VI, n = 26 dentists), visual inspection with a magnifying glass (2x; VIM; n = 26), conventional bite-wing radiography (BW; n = 24), visual inspection combined with conventional bite-wing radiography (VI + BW; n = 10), and visual inspection combined with light pressure probing (VI + P; n = 23 dentists). In order to measure the reproducibility, VI and VI + BW were repeated. After the last inspection, the teeth were histologically prepared, serially sectioned perpendicular to the occlusal surface, and diagnosed for the presence of caries. The agreement between histological and clinical diagnosis was assessed. Specificities and sensitivities were: VI = 93 and 12%, VIM = 89 and 20%, BW = 83 and 45%, VI + BW = 87 and 49%, and VI + P = 93 and 14%, respectively. The following likelihood ratios were found: VI = 1.84, VIM = 1.86, BW = 2.6, VI + BW = 3.85, and VI + P = 2.05. It was concluded that the rather low sensitivity especially for VI and VI + P may lead to a significant number of teeth with dentinal caries being undetected.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Enamel↗

PubMed2000

Production of cloned pigs from in vitro systems.

Here we describe a procedure for cloning pigs by the use of in vitro culture systems. Four healthy male piglets from two litters were born following nuclear transfer of cultured somatic cells and subsequent embryo transfer. The initiation of five additional pregnancies demonstrates the reproducibility of this procedure. Its important features include extended in vitro culture of fetal cells preceding nuclear transfer, as well as in vitro maturation and activation of oocytes and in vitro embryo culture. The cell culture and nuclear transfer techniques described here should allow the use of genetic modification procedures to produce tissues and organs from cloned pigs with reduced immunogenicity for use in xenotransplantation.

Animals↗

PubMed2003

Effect of repetitive exercise testing on breathlessness in humans.

There are conflicting reports on the reproducibility of the visual analogue scale (VAS) and the modified Borg scale for the estimation of breathlessness during exercise. In an attempt to clarify the situation, two groups of healthy subjects undertook a progressive exercise test either daily (Group A) or weekly (Group B) on 10 separate occasions. Breathlessness was estimated every 1 min using the VAS. After 10 occasions, both Group A (P <0.05) and Group B ( P <0.01) showed a significant increase in the mean intercept of the breathlessness/ventilation (VAS/ V (I)) relationship. The increase was not progressive; using change point regression, reproducible values were found to occur after approximately the fifth occasion in both subject groups. As the slope of the VAS/ V (I) relationship was highly reproducible and did not change with repeat testing, it would appear that at least two mechanisms are involved in the generation of the sensation of breathlessness. A decrease in the exercise heart rate over the same time period was significantly correlated with changes in the VAS/ V (I) intercept in both groups (P <0.01 and P <0.005 respectively). The relationship is unlikely to be causal, but may be indicative of a common underlying mechanism. It is suggested that breathlessness scores are likely to decrease as a direct result of repetitive testing over, on average, the first five periods of assessment. On the basis of this study, it may be inferred that a physiological mechanism contributes to the modulation of breathlessness during repetitive exercise testing.

Adult↗

PubMed2006

Reproducibility of cerebral blood volume measurements by near infrared spectroscopy in 16 healthy elderly subjects.

Near infrared spectroscopy (NIRS) is a non-invasive method to monitor cerebral haemodynamics. Used either alone or in combination with other non-invasive methods such as transcranial Doppler sonography, this technique is well suited for use in cerebrovascular research in ageing. Reproducibility of NIRS, however, has only been determined in neonates and adults. We applied controlled desaturation (the O(2)-method) to measure the cerebral blood volume (CBV) with NIRS in 16 healthy subjects aged 65 to 88. This method uses deoxygenated haemoglobin (the concentration of which is manipulated by desaturation) as an intravascular tracer for NIRS. We determined repeatability (between tests interval: 2 min), short-term reproducibility (intervals of 20 and 40 min) and long-term reproducibility (interval > 2 weeks). We found a coefficient of variation (CV) of 12.5% for repeatability and a CV of 11.7% for short-term reproducibility. The CV for long-term reproducibility was 15%. We conclude that NIRS can reproducibly measure CBV in subjects aged 65 and older, using the O(2)-method. In this group of healthy subjects, this method was well tolerated.

Aged↗

PubMed2002

Intra- and interobserver reproducibility of ultrasound measurements of cervical length and width in the second and third trimesters of pregnancy.

OBJECTIVES: To determine intra- and interobserver reproducibility of ultrasound measurements of cervical length and width in the second and third trimesters of pregnancy. DESIGN: Twenty healthy women in the second or third trimester of pregnancy underwent transvaginal ultrasound examination of the cervix by two examiners. Three replicate meaurements of cervical length and width were taken by each observer for each woman. Intraobserver repeatability was expressed as the difference between the highest and lowest measurement value obtained by one observer, and as the repeatability coefficient and intraclass correlation coefficient. Interobserver reproducibility was expressed as the difference between the mean of the three measurements of each observer, limits of agreement, and interclass correlation coefficient. The repeatability coefficient/limits of agreement define the range within which 95% of the differences between two measurements by the same observer/two observers are likely to fall. RESULTS: Intra- and interobserver differences did not vary in any systematic way over the range of values measured. For cervical length measurements the repeatability coefficient was +/- 5.4 mm for Observer 1 and +/- 5.9 mm for Observer 2. The intraclass correlation coefficient for cervical length measurements was 0.93 for both observers. The corresponding coefficients for cervical width measurements were +/- 3.9 mm and +/- 7.3 mm, and 0.97 and 0.91. The interclass correlation coefficient for cervical length measurements was 0.76, the mean interobserver difference was 0.4 mm, and the limits of agreement were -10.0 mm to 10.8 mm. For cervical width measurements the interclass correlation coefficient was 0.74, the mean interobserver difference was -0.02 mm, and the limits of agreement were -12.4 mm to 12.4 mm. There was no systematic difference between the first, second and third cervical length measurements and no systematic bias between the two observers, and the results were not affected by which of the two examiners started the examination (three-way analysis of variance). The same was true of cervical width measurements. CONCLUSIONS: Our results do not support the contention that the first measurement of cervical length is the longest. There is substantial intra- and interobserver variability in the results of measurements of cervical length and width, even when experienced observers perform the measurements under standardized conditions. It is important to consider the possibility of 'measurement error' when ultrasound measurements of cervical length and width are used in clinical practice to monitor women at high risk of delivering preterm or to screen for preterm birth.

Cervix Uteri↗

PubMed2004

Correction for dose-response variations in a scanning liquid ion chamber EPID as a function of linac gantry angle.

The response of electronic portal imaging devices (EPIDs) of the scanning liquid ionization chamber (SLIC) type is known to vary with linear accelerator gantry angle. This work considered several contributing factors, quantified the artefacts, monitored their reproducibility and investigated the effects of repeated gantry rotations. Unflatness of up to 5% was found. A correction technique was devised using nonlinear regression of a three-variable sinusoidal modulation. Comparison with two existing techniques found our method to be the most effective, providing a flatness well within 2%. This improved accuracy is expected to benefit more accurate dosimetric studies in particular. The post-acquisition correction process required no change in imaging protocols. Applicability of the new technique was demonstrated on images acquired on different days and with different beam sizes. Since the artefacts compromise both accurate dosimetry and image quality, their successful removal should benefit a broad range of SLIC EPID applications.

Calibration↗

PubMed2002

Optimization and evaluation of T7 based RNA linear amplification protocols for cDNA microarray analysis.

BACKGROUND: T7 based linear amplification of RNA is used to obtain sufficient antisense RNA for microarray expression profiling. We optimized and systematically evaluated the fidelity and reproducibility of different amplification protocols using total RNA obtained from primary human breast carcinomas and high-density cDNA microarrays. RESULTS: Using an optimized protocol, the average correlation coefficient of gene expression of 11,123 cDNA clones between amplified and unamplified samples is 0.82 (0.85 when a virtual array was created using repeatedly amplified samples to minimize experimental variation). Less than 4% of genes show changes in expression level by 2-fold or greater after amplification compared to unamplified samples. Most changes due to amplification are not systematic both within one tumor sample and between different tumors. Amplification appears to dampen the variation of gene expression for some genes when compared to unamplified poly(A)+ RNA. The reproducibility between repeatedly amplified samples is 0.97 when performed on the same day, but drops to 0.90 when performed weeks apart. The fidelity and reproducibility of amplification is not affected by decreasing the amount of input total RNA in the 0.3-3 micrograms range. Adding template-switching primer, DNA ligase, or column purification of double-stranded cDNA does not improve the fidelity of amplification. The correlation coefficient between amplified and unamplified samples is higher when total RNA is used as template for both experimental and reference RNA amplification. CONCLUSION: T7 based linear amplification reproducibly generates amplified RNA that closely approximates original sample for gene expression profiling using cDNA microarrays.

Journal Article↗

PubMed1990

Total respiratory compliance in infants and young children with congenital heart disease.

The multiple occlusion technique was used to measure total respiratory system compliance (Crs) in 62 infants and young children with congenital heart disease (age range, 2 days to 2 years). Measurements were found to be reproducible in nine infants in whom repeat measurements were possible (maximum deviation between measurements less than 10%). The incidence of failure to obtain accurate results was no greater than when studying infants without cardiopulmonary disease. However, in the presence of severe growth retardation or alinearity of volume-pressure data, results may be difficult to interpret in individuals. Results of Crs were related to non-invasive assessments of cardiac disease severity using chest radiography and echocardiography. After the effects of growth had been taken into account, a significant negative relationship was found between Crs and the right pulmonary artery to aortic ratio, which reflects pulmonary vascular engorgement (P = 0.003, R2 = -0.40). However, no significant relationship was found between Crs and chest X-ray score (P = 0.27).

Aorta↗

PubMed1999

Reproducibility of maximal exercise ergometer testing in patients with cystic fibrosis.

OBJECTIVES: Exercise testing in patients with cystic fibrosis (CF) has become an important tool in assessing disease severity and predicting overall outcome. The reproducibility of maximal exercise testing was examined in adult subjects with stable CF. METHODS: Nine subjects with CF underwent a total of three maximal exercise tests carried out under identical circumstances over a 28-day period. Oxygen uptake (VO2), minute ventilation (VE), respiratory frequency (f), heart rate (HR), and arterial oxygen saturation (SaO2) were measured at rest, at end exercise, and at 40% and 70% of maximum workload. RESULTS: There were no significant differences in these measurements among the three tests. Reproducibility of exercise performance was assessed using the coefficient of variation. The mean within-subject coefficient of variation for test variables at end exercise are as follows: VO2, 6.9%; VE, 6.2%; f, 5.8%; IIR, 3.0%; and SaO2, 1.1%. The mean within-subject coefficient of variation for test variables at 40% and 70% of maximal work rates are as follows: VO2, 5.2% and 4.6%; SaO2, 0.3% and 0.9%; HR, 4.0% and 3%; VE, 5.7% and 6.5%; and f, 5.8% and 7.2%, respectively. CONCLUSIONS: Variables measured during clinical cycle ergometer exercise testing in adult patients with stable CF are reproducible. No learning effect was found on repeated testing.

Adult↗

PubMed2006

When to use agreement versus reliability measures.

BACKGROUND: Reproducibility concerns the degree to which repeated measurements provide similar results. Agreement parameters assess how close the results of the repeated measurements are, by estimating the measurement error in repeated measurements. Reliability parameters assess whether study objects, often persons, can be distinguished from each other, despite measurement errors. In that case, the measurement error is related to the variability between persons. Consequently, reliability parameters are highly dependent on the heterogeneity of the study sample, while the agreement parameters, based on measurement error, are more a pure characteristic of the measurement instrument. METHODS AND RESULTS: Using an example of an interrater study, in which different physical therapists measure the range of motion of the arm in patients with shoulder complaints, the differences and relationships between reliability and agreement parameters for continuous variables are illustrated. CONCLUSION: If the research question concerns the distinction of persons, reliability parameters are the most appropriate. But if the aim is to measure change in health status, which is often the case in clinical practice, parameters of agreement are preferred.

Humans↗