Calibration – Concise Guide

This is a concise version of the Society for Psychical Research (SPR)’s guide to calibrating equipment for paranormal investigations.

Why Calibrate?

• Ensures greatest accuracy.

• Allows comparison of data from different devices.

Comparative Calibration

• Use one device as the master reference.

• Place devices together (e.g., thermometers in a box for 10+ minutes).

• Note differences → apply correction factors to non-master devices.

• Works for thermometers, EMF meters, and other environmental devices.

• For precision, compare across varied conditions (hot/cold).

Set the Time

• All devices and team members must use the same time reference.

• Choose a master (smartphone preferred for accuracy).

• Synchronize: data loggers, cameras, recorders, and personal watches.

Analogue Devices

• Many allow manual adjustment (e.g., screw setting).

• Align display with known conditions.

Commercial Calibration

• Some equipment can come with or be sent for certified calibration.

• Useful only if highly accurate data is required.

• Expensive and must be repeated periodically.

Emissivity (for thermal devices)

• Adjust for material surface properties (range 0–1).

• Most building materials: 0.90–0.98.

• General use: set to ~0.95–0.98.

• Ensure all similar devices use the same emissivity factor.

Best Practices

• Always check settings before each investigation.

• Label each device with its correction factor.

• Recalibrate at least twice per year.

• Never assume accuracy just because a device was calibrated—verify.

Further Reading

• Using Equipment: Guidance Notes for Investigators (SPR) – available via SPR website or Amazon.

- C.E.

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