BCal help system: The Tutorial

Step A13: Calibration curve elicitation

The calibration curve elicitation page allows us to select the calibration curves to use. A calibration curve must be assigned to each determination parameter. Which calibration curve we use depends on the origin of the sample represented by the determination parameter.

In our example, Layer III has one determination parameter (theta 1). theta 1 represents the true calendar date of a sample that metabolised in an atmospheric environment. Consequently, we should use the atmospheric curve for this determination parameter. Layer II has four determination parameters (thetas 2 to 5). The corresponding samples all metabolised in a marine environment and so we should use the marine curve for these.

In this example, most of the determination parameters require the marine curve. We should, therefore, use this as the master curve. All determination parameters will use this curve, unless otherwise specified. Since theta 1 from Layer III requires the atmospheric curve, we need to set theta 1 ourselves in the section below. This will override the master curve selection.

BCal allows us to choose whether or not the errors in the calibration curve should be incorporated into the calibration process. The default is to use the errors. We recommend that the errors in the calibration curve should always be used, unless you understand the consequences of not using them. To use the errors, we just leave the "errors" check box as checked.

At the bottom of the page is the "Apply to all" checkbox. This allows us to apply the master curve to all determination parameters, regardless of their individual settings. This is useful only when making changes to an existing calibration definition and should be left unchecked.