Glossary of a CRO: I

We begin a line of content under the name “Glossary of a CRO” in which we will do a brief and concise (but important) explanation of the most common terms in the day-to-day of the trials.

Deviation of a study protocol

An event that was not considered in the original protocol. These deviations must be recorded, as well as the reason that caused them. In addition, the name and signature of the investigator describing the deviation must appear.

Control product

Any product authorized prior to the start of the trial that is used in a study for comparison with the veterinary product in research.

Control group and experimental group

  1. The control group refers to the group of subjects in a clinical trial that does not receive the treatment to be investigated. Like the control product, this group is compared with the one that does receive the new treatment in order to know its level of safety, efficacy and quality.
  2. The experimental group is the one to which the drug is administered and on which the effects that it generates in the subjects, the benefit / risk ratio, the optimal dose, … will be observed (the information obtained will depend on the design of the study protocol.


In field trials, it refers to the process of assigment of a part of the subjects to a treatment or control group. It is done in order to avoid bias and ensure objective comparability.

With this technique, we leave to random or chance the type of treatment that each subject will receive.

Blind / Masking

Procedure designed to reduce the bias of a study in which some of the participating parties does not know the allocation of each treatment. Common methodologies:

  • Single blind: Only the subjects receiving the treatment are unaware of what they have received (this concept only has a place in human research).
  • Double blind: When the investigators also ignore the treatment each subject receive.
  • Triple blind: In this case, subjects, investigators and personnel that analyzes de data do not know the treatment for each subject. This methodology Is used when the clinical variables can be interpreted in different ways.


Assurance and prevention of the revelation to non-authorized parts of the information that belongs to the sponsor of the study.


Supervision of the progress of a trial in order to ensure that it is carried out, recorded and reported in accordance with the protocol, Standard Operating Procedures (SOPs), Good Clinical Practices (GCP) and relevant regulatory requirements. In our post “Clinical Trials Monitoring” we discuss this concept further.

Monitoring report

Report written by the monitor that contains information obtained after each visit to the test site or communication related to it.

Data Collection Logbook (DCL)

Printed or electronic documents designed according to the information required in the study protocol. In them, all pertinent data are collected and recorded, which will later be analyzed for the statistical analysis.

All trials (clinical, nutritional, …) require of DCL in order to record the data in a standardized way and to save the information basing on a single order and criteria. Thus, It will facilitate reliable data and make decisions.

Adverse Event

Any unfavorable reaction that occurs in a clinical research subject who is administered with a pharmaceutical product, and that may not have a causal relation with that treatment. An adverse event can therefore be any unfavorable and unexpected sign (including an abnormal laboratory finding), symptom, or disease temporarily associated with the use of a medicinal product (under investigation), whether or not it is related to this product.


Follow-up of all the requirements established in the Good Clinical Practices (GCP) and the pertinent regulatory requirements.

Raw data

Data that comes directly from the data collection source. It includes all the information contained in original documents (from clinical findings, CRF’s data record, observations, and any other activity of a clinical trial).

Correct management and analysis of the data collected in the field is essential to get reliable and objective study results, providing information that guides towards  decision-making. To do this, we must take into account the training and experience of those responsible for this critical phase. Contact our team of statisticians if you need to refer these tasks to a company like T&T, where we have been helping companies understand their data for more than 20 years.

Accuracy and precision

Essential terms in our work and that inspired our slogan. We don’t get too complicated: “Accuracy and Precision”:

  • Accuracy: It is defined as the proximity between the measured value and the “true” value of the measurand. It refers to how close to the actual value the measured value is. In statistical terms, the accuracy is related to the bias of an estimate. The smaller the bias is, the more accurate an estimate.
  • Precision: It refers to the dispersion or spread of the set of values ​​obtained from repeated measurements of a magnitude. It is expressed numerically through measures of dispersion (standard deviation or variance), so the smaller it is, the better. It is necessary to have several measurements to calculate it. It depends on the distribution of the results and is not related to the true value of the measurement.

Experimental unit

It is the FIRST step to calculate the sample size and refers to the smallest unit on which a certain characteristic or measure is obtained. We apply the treatments to more than one experimental unit to increase the reliability of the study and to ensure that we have representative data. We intend to maximize the precision of the estimates of the parameters of interest.