Accuracy in pumping terms is an expression of how close the fluid flow rate delivered by the pump matches the numerical value of the fluid flow you entered into or requested via computer.
Pump manufacturers will offer specification sheets declaring their pump’s accuracy. They are all pretty good.
Of all the different types of pump available, syringe pumps are recognized as the most accurate and repeatable devices for low volumes and low rate fluid delivery.
What effects accuracy?
Your fluid. The viscosity of your fluid can really effect the pumping accuracy.
Your plumbing. The length of tubing, the dimensional stability of the tubing (does it inflate like a balloon or is it rigid), the fittings (number and type) and the destination device can all effect the ability of the pump to output fluids. This can all be rate dependent too.
Your pump’s mechanics. A syringe pump with a non-rigid frame, and low quality components will have mechanical slack in it which will effect the rate at the start of pumping and at direction of pumping reversals.
Other things: the number of rotational steps the pumps drive motor has, in combination with the torque of that drive motor, the control of the motor drive electronics, any gear chain or belt drive mechanism.