Test - Quant Tests

Quantifies the agreement between two measurement methods, considering measurement errors. A maximum allowable difference from 1 is standard. $VR = \frac{Var(X) + Var(Y)}{Var(X - Y)}$ $Var(X)$ = Variance of X $Var(Y)$ = Variance of Y

Measures the strength and direction of the linear relationship between two measurement methods using Passing Bablok regression. A minimum absolute value of 0.95 is standard for strong correlation. $r = \frac{Cov(X, Y)}{Var(X) + Var(Y)}$ $Cov(X, Y)$ = Covariance of X and Y $Var(X)$ = Variance of X $Var(Y)$ = Variance of Y

Measures the strength and direction of a monotonic relationship between two variables. A minimum absolute value of 0.95 is standard for strong correlation. $p = 1 - \frac{6 \sum d_i^2}{n(n^2 - 1)}$ $d_i$= Difference between ranks of X and Y $n$ = Number of pairs

The sample correlation coefficient (R) quantifies the strength and direction of the linear relationship between two variables based on sample data. A min value of 0.95 is standard. $R = \sqrt{r^2}$ $r^2$ = Coefficient of Determination

Measures the strength and direction of a linear relationship between two variables. A minimum absolute value of 0.95 is standard for strong correlation. $r = \frac{Cov(X, Y)}{\sigma_X \sigma_Y}$ $Cov(X, Y)$ = Covariance of X and Y $σ_X$ = Standard Deviation of X $σ_Y$ = Standard Deviation of Y $Cov(X, Y) = \frac{1}{n-1} \sum_{i=1}^{n} (x_i - \bar{x})(y_i - \bar{y})$ $n$ = Number of data points $x_i$ = Individual data point of variable $Xy_i$ = Individual data point of variable Y $\bar{x}$ = Mean of variable X $\bar{y}$ = Mean of variable Y

Measure of how much a high concentration sample influences the result of a subsequent low concentration sample. $\text{Carryover (\%)} = \frac{\text{Low Diff}}{\overline{\text{High}} - \overline{\text{ Low-Low}}} \times 100$ ${\overline{\text{High}}}$: Average of High results ${\overline{\text{Low-Low}}}$: Average of Low-Low results

The subtracted difference between the first and last Low Concentration samples. $\text{Low Diff} = \text{Low Rep 1} - \text{Low Rep 3}$

A result from a low sample tested directly after testing a high sample

A result from a low sample tested directly after testing a low sample

The percent of the population results that must be within the Reference Interval for it to be confirmed. We recommend a 95% to match with statistical confidence intervals for populations.

The minimum number of eligible samples required in order for the Reference Interval to be set. For a verification we recommend minimum 20 samples.

A statistically calculated line in the notation of Y = mx + b that represents the linear relationship between two datasets. $y = mx + b$ $m = \frac{n(\sum xy) - (\sum x)(\sum y)}{n(\sum x^2) - (\sum x)^2}$ $b = \frac{\sum y - m \sum x}{n}$ m: The slope of the line, which indicates how much y changes for a unit change in x. b: The y-intercept of the line, which is the value of y when x=0. n: The number of data points or observations in the dataset. x: The independent variable values in the dataset. y: The dependent variable values in the dataset.

A calculated value from the LoQ Allowable Error % (k) and the LoQ Reference Value which returns the maximum TE result acceptable from an LoQ Experiment. $LoQ\ Allowable\ Error\ \% = Reference\ LoQ\ Value \times \frac{k}{100}$ Reference LoQ Value: The validated LoQ concentration determined during validation k: LoQ Allowable Error

The manufacturer stated LoQ determined through validation.

Total Error for LoQ represents the calculated error at the low concentration. $TE=σ+2×Bias$ σ: Standard Deviation of the results Bias: Difference between mean of samples and reference value

LoQ Allowable Error (k) sets the LoQ precision by scaling the LoQ Reference Value. With a general standard of 10%, a higher value increases statistical confidence.

Mean of all the Error Indexes calculated from a group of samples. A large distance from 0 can indicate a shift or Systematic error between the Actual and Reference result values.

Range of values from lowest to highest that was measured within a group of samples.

R-squared is a statistical measure that represents the proportion of the variance in the dependent variable that is explained by the independent variables in a regression model. It ranges from 0 to 1, with higher values indicating a better fit. Usually >0.95 is considered statistical correlation. $R^2 = 1 - \frac{\sum_{i=1}^{n} (y_i - \hat{y}i)^2}{\sum{i=1}^{n} (y_i - \bar{y})^2}$ $R^2$ = Coefficient of determination $y_i$ = Observed value $\hat{y}_i$= Predicted value $\bar{y}$ = Mean of observed values $n$ = Sample size

The type of error (TEa, SEa or REa) that will be used for calculating Error Index agreement between two results.

The lowest concentration of an analyte that can be reliably detected by a test, distinguishing it from zero or background noise.

A value or determination collected by measurement or calculation.

In MV experiments, the Results Per Day is the number of replicate measurements that will be taken per day.

Days refers to the number of distinct days on which a test is repeated to assess the consistency of results over time.

The total number of measurements between actual and reference value in agreement.

The ability of the test to correctly identify true negatives. $\text{Specificity} = \frac{\text{TN}}{\text{TN} + \text{FP}} \times 100\%$

The ability of the test to correctly identify true positives. $\text{Sensitivity} = \frac{\text{TP}}{\text{TP} + \text{FN}} \times 100\%$

The proportion of negative test results that are true negatives. $\text{NPV} = \frac{\text{TN}}{\text{TN} + \text{FN}} \times 100\%$

The number of false positive results where the test incorrectly detected the presence of the substrate when compared to the reference method.

The number of false negative results where the test incorrectly missed the presence of the substrate when compared to the reference method.

The number of true negative results where the test correctly identified the absence of the substrate when compared to the reference method.

The number of true positive results where the test correctly detected the presence of the substrate when compared to the reference method.

The minimum percentage of agreement required between the test results and the reference results from the acceptance criteria for the experiment to pass.

A specimen provided by an external quality assessment organization to participating laboratories for testing. The results from these samples are used to evaluate the laboratory's performance and accuracy by comparing it against a benchmark or other participating laboratories.

External Quality Assessment (EQA) evaluates a laboratory's performance by comparing its results with other labs through external sample testing. This ensures accuracy and consistency in diagnostic testing.

Information about a test relevant to the description, background and performance metrics.

Multiple tests on the same sample to assess precision and repeatability, conducted within a run or across multiple runs.

Reference methods are well-established, highly accurate, and precise analytical procedures used as standards to evaluate the performance of other methods.

Value from Qualitative or Semi-Quantitative set in Tests that expresses non-detection of the measured substrate.

An Acceptance Criteria of the minimum number of eligible samples required in order for the evaluation’s requirements to be fulfilled.

Samples that provide the necessary information for statistical calculations to be performed. Usually this is possessing both an actual and expected result.

An MV experiment used to evaluate the effect of interfering substances on sample concentration measurements.

The effect of high concentration measurements on subsequent low concentration samples.

An MV experiment used to evaluate the effect of high concentration testing on subsequent low concentration samples.

An experiment used to determine the normal ranges for a test within populations measured by the laboratory

An MV experiment used to estimate the systematic difference on the basis of the differences observed between the methods. See: QL Method Comparison

Lab Contact is the primary contact method of reaching a laboratory. This can be an email, phone number or name.

A label used in a Qualitative test to express a that a sample has detectable levels of substrate

A label used in a Qualitative test to express a that a sample does not have detectable levels of substrate

The standardized measurements used to express the quantity of a substance or the outcome of a test.

A concise, 12-character maximum shorthand for a test, such as ALT for Alanine Aminotransferase.

Substance or chemical constituent being measured or analyzed.

An Interfering Substance (IF) is an external or endogenous compounds that can alter the outcome of a laboratory test by affecting the test's reagents, analytes, or measurement process.

Classifications used to segment reference intervals based on specific characteristics of the population such as age or gender.

The range of values that includes the central 95% of a healthy population's test results. It is derived from a large sample of healthy individuals to ensure accuracy and reliability. It is often considered the normal range of results for a healthy person.

An error in measurement caused by factors which vary from one measurement to another.

A unique identifier for the analyzer. Usually the Serial Number provided by the manufacturer.

A shorter human readable designation given to an analyzer used to distinguish it in common workplace discourse (eg Blue CBC). This is primarily how your analyzer will be displayed while navigating in Cualia.

The name of the analyzer, usually the model's name provided by the manufacturer.

Cualia includes a library of analyzers, tests, analytes and TEas to include in your organization to get started quickly. General profiles of Laboratory Developed Analyzers can also be used as a template.

This name will be used for report signing and will be the same across all organizations you are a member.

The member’s role within an organization or laboratory such as Department Head or Lab Personnel

The initiation process to set up your user profile and organization’s lab details.

An MV report documents analyzer details, tests, and results for submission to accreditation bodies.

The proportion of the Bias to the Error Allowance. An Error Index must be between -1 and 1 to be considered in agreement.

The Range between the lowest and highest value

A Test Result Type that produces Results as a numerical value within a Range.

Defined Quality objective/target/goal/criteria for the laboratory to meet.

An organization or government agency responsible for offering accreditation or qualifications for medical laboratory testing.

The name of the Cualia member that performed the analytical testing

A systematic process to evaluate whether the performance of a medical Test meets quality goals set by a validation. Performance evaluations may usually be found in a manufacturer insert.

Range between the lowest and highest concentrations of an analyte that a test can accurately measure without dilution or concentration.

A sample of similar matrix to method's expected sample with none of the analyte present. Oftentimes this can be a zero standard from a calibrator.

A sampling of results that are statistically analyzed and interpreted in the evaluation of testing performance.

The value/result that represents the true value from a trusted reference source such as a verified instrument, EQA, or a commercial product.

Combined Results across Runs of the same Level on the same run, day or time period. Oftentimes a run load volume can be instrument specific and “Within Day” is commonly used. Other Names → Intra-Assay

An Approval Status for an MV where work is in progress. In this state the MV can be edited.

Can describe the specific Sample Type, source and/or medium that is used to collect and/or store the sample.

The Mean of the Error Index's within a collection.

The principle mechanism or technology utilized by a system such as Radio Immunoassay or RT-PCR.

A performance metric for a test determined by the Manufacturer through Validation

When two values, based testing requirements and Error Allowance are outside of acceptable agreement.

The difference in Results when comparing laboratory Quantitative methods with established methods.

A prepared sample, often using a Blank that has been "spiked" with a measurable analyte.

Average value amongst a sample group

A broad term that can be used synonymously with Performance Evaluation, Method Validation and/or Method Verification.

The maximum amount of Random Error allowed for two results to be in agreement

An is the highest concentration of analyte detected for a blank sample. This can be determined through the LoB MV Experiment. $LoB=μ+1.645×σ$ $μ$: Mean of the results $σ$: Standar Deviation of results

A reference Level within a range to determine performance around that value.

Statistical measure of the amount of variation from the mean. $\sigma = \sqrt{\frac{1}{n-1} \sum_{i=1}^{n} (x_i - \bar{x})^2}$ σ = Standard Deviation n = Sample Size $x_i$ = Individual data point $\bar{x}$ = Mean

A specific location within the organization where laboratory tests and analyses are conducted.

The status of an Experiment or MV. Either Drafting, Under Review or Approved.

The original source of the Sample such as Sample, EQA, or the name of the Manufacturer.

A Result Type for a Test that can only have two possible options

A Testing System is a product, model, system or a developed process/method used in the medical laboratory setting for performing analysis of clinical samples. This can represent a system offered a Manufacturer or an LDT

In Qualitative testing a matching pair of Actual and Reference Results are considered in Agreement

An Approval Status for an MV that has been approved by the lab and ready for audit by a regulatory assessor.

Quantitative Agreement uses Error Allowance as TEa or its counterparts REa, SEa, or a Custom Error rate. Actual and Expected are in Agreement when the Bias between the Results is less than the Error Allowance and the Error Index is less than 1.0

Analytical range at which a method's results is verified. A Linearity experiment is used to determine this range. Reportable range means the span of test result values over which the laboratory can establish or verify the accuracy of the instrument or test system measurements response.

The systematic process and documentation of efforts to reach or maintain Quality Standards.

An experiment that evaluates Random Error through replicate measurements across concentration levels.

An MV Experiment used to determine the lowest "reliable" value measured from a test

The general identification used to identify a specific Sample.

A systematic process to evaluate whether the performance of a medical Test meets quality goals to be used for medical testing.

A specialized division within a lab that focuses on particular types of tests or medical disciplines.

Ratio of the Standard Deviation of the Mean, often expressed as a percentage. See: CV%. It provides a relative comparison of the Standard Deviation independent of the size of the value. $\text{CV} = \frac{\sigma}{\mu}$ $\sigma$ = Standard Seviation ${\mu}$ = Mean

Range of analyte values that a method can measure, allowing for specimen dilution, concentration, or other pretreatment used to extend the direct analytical measurement range. The distinction between CRR and RR is that CRR may be up to the medical director's discretion of what range of results to report.

Actual represents the real-world value measured by the instrument being evaluated.

Trueness is an MV Experiment that evaluates the performance of a test by comparing sample test results with true values. Usually an EQA.

The top-level entity representing the overall institution, such as a hospital, clinic, or laboratory network.

An instrument/kit used to perform tests

The type of result, either Qualitative, Semi-Quantitative, or Quantitative that Test Result can offer.

Individual specimens collected for testing representing the source. In MV experiments with Runs, this can refer to to the number of concentration levels used.

The name of the Testing System manufacturer that produced the instrument.

Statistically generated summary data used to represent the collection

A Quality Control material, usually developed by a manufacturer, with a known Expected Result used for monitoring Test performance.

A document from the Manufacturer of a Test providing details on Manufacturer Claims, Procedures, warnings and any other considerations for testing.

A method developed by the laboratory or a regulator approved/validated method that has been modified.

Values Qualitative or Semi-Quantitative set in Tests that can express a Result that indicates a Positive Result.

A consistent, predictable error that skews results in a specific direction. Systematic errors affect the accuracy of the test results, leading to a consistent deviation from the true value.

A set of experiments performed to validate/verify a test procedure.

The set limit of combined REa and SEa tolerable for a single result. It represents the error range around an Expected result that can be considered in Agreement to an Actual result. TEa = REa + SEa

Linearity is an MV experiment to establish the correlation between Reference and Actual Results

Coefficient of variation expressed as a percent

A Test is a process used to determine the presence or concentration of a substrate.

An MV Experiment used to determine the lowest amount of analyte that can be reliably determined.

A sequence of measurements on a set of samples under the same conditions, performed within a defined time period.

Whether two values, usually the actual and reference values acceptably agreeable, based on testing requirements and/or Error Allowance.

An Approval Status for an MV where the work is prepared and ready for evaluation by another laboratory member.

Comparison of Run replicate measurement(s) that occur on different runs/days. Other Names → Inter-Assay

A material, such as a reagent, control, or calibrator used to execute a procedure or process

Acceptable shift across the detectable range of a test in a single direction.

A 5 Day Test is a standardized procedure used for method validation/verification and experiments in clinical and medical laboratories. It involves performing 5 replicates/results in each of the 5 runs conducted over a course of 5 days to ensure precision and accuracy of the method.

The percentage (%) of paired Results within Agreement amongst the number of Samples measured. $\text{Agreement \%} = \left( \frac{\text{Results in Agreement}}{\text{Total Number of Comparisons}} \right) \times 100$

The probability that a Positive Result indicates the Expected analyte Result is a positive. $PPV = \frac{TP}{TP + FP}$