What are the main elements that diagnose and evaluate the efficiency of any test you perform in the laboratory?

Dear All, = In any test we perform, either in medical or chemical laboratory works, or even at software or engineering testing tasks, we have to insure that our analytical work and the data we obtained from must be evaluated under certain parameters in order to confirm the testing method efficacy.
Again, our role can be summarized in comparing the "Diagnostic Efficacy" of various laboratory tests and determining the most useful test (when we have multiple methods to test one thing, or the scheduled tests we worked on them).
= Diagnostic Efficacy consists of three axes: Sensitivity, Specificity and Predictive value.
I will try to explain those terms from my medical point of view, because it lies within my specialties background.
Otherwise, may others have different opinions considering those terms, and whatever our answers were, should be in the same boat.
=1= Sensitivity (and here is meant as diagnostic sensitivity) is: -=- the proportion of individuals with such a disease who test positively with the test.
Sensitivity is usually expressed as a percentage (%) and presented as follows: -=- Sensitivity =100x No.
of diseased individuals with positive test / total No.
of diseased individuals tested.
-=- Diagnostic Sensitivity should not be confused with Analytic sensitivity, in which the second term can be referred to as the smallest concentration that can be measured accurately and can be expressed in another term known as "Detection Limit".
=2= Test Specificity is defined as the proportion of individuals without the disease who test negatively for that disease.
Specificity is also expressed in percentage (%) as follows: -=- Specificity =100x No.
of individuals without a disease with negative test / Total No.
of individuals tested without the disease.
-=-Most of us overlap this term with instrumental specificity term, which refers to a method's ability to measure only the analyte of interest.
= Sensitivity and specificity have much in common and work on: - Depending on test results distribution for the diseased and non-diseased persons and also the test values that define the abnormal levels.
- The sensitivity can be increased by decreasing the test value, while specificity will be decreased by the test value decline.
- So, few laboratory tests with sensitivities and specificities close to100%, but most tests have both values that are close to50%.
It is suggested that if the sum of the sensitivity and specificity of a test is ~100%, the test is no better than a coin toss.
- Other method can be used for both calculation, is defined from using the following terms: True Positive (TP; patients with a disease and classified by a test to have it), True Negative (TN; patients without a disease and classified by a test not to have it), False Negative (FN; patients with a disease and classified by a test as disease free), and FP (patients without a disease and incorrectly classified by a test as having the disease).
- By those terms, Sensitivity may be calculated as =100 TP(TP + FN), and Specificity =100 TN(TN + FP).
=3= Predictive value test is the proportion of individuals in the population who have the disease, and can be expressed as a function of sensitivity, specificity and disease prevalence.
-=- Predictive value can be for positive tests (PV+) and for negative tests (PV-); by which: PV+ (%) =100 TP/(TP + FP), and PV- (%) =100 TN/(TN + FN).
== If anyone has a comment or additional notes on my answer, he/she can add a value by his/her knowledge and share others with effective thoughts.

The diagnostic process occurs within a work system that is composed of diagnostic team members, tasks, technologies and tools, organizational factors, the physical environment, and the external environment

 

• Diagnostic team members include patients and their families and all health care professionals involved in their care.
• Tasks are goal-oriented actions that occur within the diagnostic process.
• Technologies and tools include health information technology (health IT) used in the diagnostic process.
• Organizational characteristics include culture, rules and procedures, and leadership and management considerations.
• The physical environment includes elements such as layout, distractions, lighting, and noise.
• The external environment includes factors such as the payment and care delivery system, the legal environment, and the reporting environment.

professionalism and accuracy combined with concentration consistancy

1- accuracy2-precision

Consistency when the tests are repeated with the same sample.

Precission (extent of senstivity of equipment/method to detect minute diffrences) and Accuracy (extent of difference observed results and actual results).

Take professional approaches, folow SOPs (Standard operating Procedures) to minimize Personal errors and reduce systematic errors.

1-Sensitivity

2-Specificity

3-Predictive value

A good laboratory tests should be able to distinguish the subjects suffering from a disease compared to healthy. These parameters are referred to as "diagnostic sensitivity" and "diagnostic specificity" which should not be confused with the sensitivity parameters and analytical specificity

It 'important to note that the sensitivity and specificity are interdependent. The sensitivity and specificity of the diagnostic tests are calculated by the formulas:

Diagnostic sensitivity = VP / (TP + FN)

Diagnostic Specificity = VN / (FP + VN)

Where VP (true positives) is the percentage of subjects with positive test; FP (false positives) is the percentage of positive tests in healthy subjects; FN (false negatives) is the percentage of patients with negative test; VN (true negatives) the percentage of healthy individuals, adverse to the test.

Quality assurance .Quality control,  accuracy combined with concentration consistancy, A &   with your profissoiality clinical sense with acase of your pateint

to belive that no matter what >>> keep your hope alwayes up to the sky as your limet should be .

Diagnostic Efficacy consists of three : Sensitivity, Specificity and Predictive value.

understand what you are doing