Polygraph Suite: an ESS-M, CIT, and FROSS calculator that never leaves your device
A multilingual (Ukrainian, English, Spanish) calculator for scoring psychophysiological detection of deception (PDD) results using three validated scientific methods — online and offline, no registration, no data ever sent over the network.
What Polygraph Suite is
Polygraph Suite is a free calculator for polygraph examiners, built for scoring psychophysiological detection of deception (PDD) results using three validated scientific methods: ESS-M, CIT, and R&I (FROSS). The application is available in three languages — Ukrainian, English, and Spanish — and is intended for practicing professionals.
The application was developed by PLGRPH — the same credibility assessment center that has been conducting polygraph examinations since 2013 and provides methodological support to examiners.
You can try the calculator directly at plgrph.com/ps/en/ — no installation required for the browser version.
Zero-Server architecture: why it matters
Psychophysiological examinations involve sensitive personal data. For this category of information, how the data is stored matters as much as the accuracy of the scoring method itself.
No server infrastructure
The application never sends data to a backend, because there is no backend to receive it.
Local storage
Session data lives in the browser's localStorage; note images are stored in IndexedDB on the user's device.
Online and offline
The web version works without a network connection after loading; a standalone offline build is also available.
Any operating system
No dependency on a specific OS — the application runs in a browser on Windows, macOS, and Linux.
Three validated scientific methods
Each tab of the calculator implements a separate, self-contained scoring method — covering different test types and different tasks within a polygraph examination.
ESS-M
Empirical Scoring System — Multinomial. An updated version of ESS, published by Raymond Nelson in 2017. Uses a Bayesian classifier with a multinomial distribution to analyze comparison question test (CQT) data. Supports both screening and diagnostic formats, with separate scoring of five physiological channels: thoracic and abdominal respiration, electrodermal activity (EDA), cardio, and photoplethysmography (PPG).
- Verdict: SR / NSR / NO or DI / NDI / INC
- 5 physiological channels scored separately
- DLST, DLDT, LEPET, AFMGQT, BOST, Federal, Utah formats
CIT
Concealed Information Test, proposed by David Lykken in 1959. The scoring system is based on the Lykken probability matrix, which allows a statistical estimate of the probability that an examinee possesses information unavailable to an innocent person.
- Lykken probability matrix
- Verdict: RI / NRI / NO
- Based on the orienting response theory
R&I / FROSS
Field Rank Order Scoring System ("High Three") — a ranking method for analyzing relevant and irrelevant questions. FROSS is a supplementary, secondary method: it does not determine the SR/NSR/NO verdict — that decision is always made globally by the examiner. The method indicates which relevant question is most significant for further follow-up investigation.
- Does NOT determine the verdict on its own
- Ranking of 5 relevant questions across 3 channels
- Significance chart: top 3 highlighted by color
Comparing the methods
| Method | Test type | Scientific basis | What the verdict shows |
|---|---|---|---|
| ESS-M | Comparison (CQT) | Bayesian multinomial classifier (Nelson, 2017) | SR/NSR/NO or DI/NDI/INC — an independent verdict across 5 channels |
| CIT | Concealed information | Lykken probability matrix (1959) | RI/NRI/NO — probability of possessing concealed information |
| R&I / FROSS | Screening, ranking | Krapohl, Shaw (2015); Krapohl, Senter, Stern (2005) | Ranking of questions — NOT an independent verdict |
Scientific sources
- Nelson R. (2017). Multinomial reference distributions for the Empirical Scoring System. Polygraph and Forensic Credibility Assessment, 46(2), 81–115.
- Nelson R. (2016). Scientific (analytic) theory of polygraph testing. APA Magazine, 49(5), 69–82.
- Krapohl D.J. (2010). Reference Guide for the Empirical Scoring System — Multinomial (ESS-M). Lafayette Instrument Company.
- Lykken D.T. (1959). The GSR in the detection of guilt. Journal of Applied Psychology, 43(6), 385–388.
- Krapohl D., Shaw P. (2015). Fundamentals of Polygraph Practice, p. 122.
- Krapohl D., Senter S., Stern B. (2005). An exploration of methods for analysis of multiple-issue relevant/irrelevant screening data. Polygraph, 34(1), 47–61.
Auxiliary tools
Notes
A Markdown editor for the examiner's observations during the examination. Supports attaching images (JPG/PNG/WEBP, up to 5 MB per file, up to 20 files) and documents (PDF/DOC(X)/XLS(X)/PPT(X)/TXT, up to 20 MB per file, up to 20 files). All attachments are stored locally, the same as the rest of the session data.
Supervision
A second examiner enters their own ESS-M scores alongside the originals — the original scores remain unedited. The system shows discrepancy markers in real time for every cell of the table, along with a summary: how many scores match, the total discrepancy, and it directly names the most problematic physiological channel — the one, out of five, with the highest sum of discrepancies. Useful for training junior examiners, quality control, and mentoring.
Who this tool is for
Polygraph Suite is designed for practicing professionals across three language segments. The tool is not a training manual for students or newcomers to the method.
Independent practicing examiners
A personal working tool for scoring results and a portable archive of calculations.
Departments and agencies with several examiners
Sharing results between colleagues and collaborating on the same examinee.
Supervisors and senior examiners
Quality control over subordinate examiners' work via the Supervision tab.
Extended usage scenarios
Exchange between examiners for repeat testing
A second examiner conducting a follow-up examination of a previously tested individual opens the received session file in their own copy of the application — all data, notes, images, and documents are fully restored. They then add their own test to the same session.
Sending results to a supervisor or client
The recipient opens the same free application via the link, without registering, and imports the file — a simple, accessible step rather than a barrier for someone seeing the application for the first time.
Supervision by a manager or senior examiner
The supervisor opens the file in the same application, switches to the Supervision tab, enters their own scores alongside the original (unedited) ones, and sees discrepancy markers in real time.
Identifying systematic misinterpretation of individual channels
A repeated independent scoring by a supervisor reveals a discrepancy after comparison — and the system automatically points to the problematic channel based on the sum of discrepancies. This reveals a systematic error by a specific examiner, not a one-off occurrence.
Secure exchange of a file with sensitive data
Transmitting a results file over channels that do not guarantee confidentiality — a password-protected .pgse file is useless without the password, sent through a separate channel.
Print or PDF report for a client
The built-in print function produces a clean, structured output (without interface controls) with tables and a conclusion, saved as a PDF through the browser's standard print dialog.
Personal archive of calculations
Each session is saved as a separate, auto-named file (examinee name + date) — a portable file that the user organizes independently on their own device or in a cloud storage of their choice.
Calculator interface
An overview of the application's main tabs.
Online and offline: two ways to use it
Polygraph Suite can be used directly in a browser with an internet connection, or fully standalone, without a network.
Online version
Opens at plgrph.com/ps/en/ in any modern browser. Once the page has loaded, further work and calculations do not require additional network requests — all libraries are local.
Offline build
For work in places without a stable connection — field examinations, secure facilities, areas without coverage — a standalone build of the application is available as a set of files. It opens directly from the device, no internet required.
The offline build runs on any operating system:
Security and file sharing
Standard export
.json — without images and documents, or .zip — with images/ and documents/ folders, with automatic file naming.
Password-protected export (.pgse)
A separate button with a yellow-lock icon encrypts the entire file using AES-256-GCM (key derived from the password via PBKDF2-SHA256, 150,000 iterations), entirely on the client side through the built-in Web Crypto API. The file is useless without the password, which is sent through a separate channel.
Smart import
The application automatically detects the file format (regular or protected) and asks for a password only when needed.
Compared to manual scoring
ESS-M, CIT, and R&I can also be applied manually — on paper or in a custom-built Excel spreadsheet. The key difference of a dedicated calculator lies not in the method itself, but in how it's applied.
Manual scoring / Excel
- Manual summation of scores — risk of arithmetic errors
- Visualizations need to be built independently
- Table format and approach vary from one examiner to another
- File sharing carries the risk of discrepancies in table structure
Polygraph Suite
- Score calculation is automated — arithmetic errors are eliminated
- The FROSS significance chart and discrepancy markers are generated automatically
- A single standardized approach across sessions and examiners
- The exchange format (.json/.zip/.pgse) is consistent and compatible between copies of the application
Frequently asked questions
Is it safe to store polygraph results in Polygraph Suite?
What is the difference between ESS and ESS-M?
Can Polygraph Suite be used offline, without an internet connection?
How much does Polygraph Suite cost?
Can I share results with a colleague for review?
What is FROSS and why is it needed?
Is registration or an account required?
How does the password-protected export (.pgse) work?
Can Polygraph Suite be used for team work in an agency?
How does Polygraph Suite differ from manual scoring in Excel?
Can I print or save the result as a PDF?
Which operating systems does the offline version support?
Try Polygraph Suite
The calculator is available directly in your browser, with no registration or installation. For offline work — the standalone build is available upon request.