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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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1272 PROBIT<br />

RMP Relative median potency. Display the relative median potency (RMP) of each pair<br />

of groups defined by the grouping variable. PROBIT displays this default output for<br />

single-predictor models only. For any pair of groups, the RMP is the ratio of the stimulus<br />

tolerances in those groups. Stimulus tolerance is the value of the predictor<br />

necessary to produce a 50% response rate. If the derived model for one predictor and<br />

two groups estimates that a predictor value of 21 produces a 50% response rate in<br />

the first group, and that a predictor value of 15 produces a 50% response rate in the<br />

second group, the relative median potency would be 21/15 = 1.40. In biological<br />

assay analyses, RMP measures the comparative strength of preparations.<br />

PARALL Parallelism test. Produce a test of the parallelism of regression lines for different<br />

levels of the grouping variable. This test displays a chi-square value and its associated<br />

probability. It requires an additional pass through the data and, thus, additional<br />

processing time.<br />

NONE Display only the unconditional output. This option can be used to override any<br />

other specification on the PRINT subcommand for PROBIT.<br />

ALL All available output. This is the same as requesting FREQ, CI, RMP, and PARALL.<br />

MISSING Subcommand<br />

PROBIT always deletes cases having a missing value for any variable. In the output, PROBIT<br />

indicates how many cases it rejected because of missing data. This information is displayed<br />

with the DATA Information that prints at the beginning of the output. You can use the<br />

MISSING subcommand to control the treatment of user-missing values.<br />

EXCLUDE Delete cases with user-missing values. This is the default. You can also make<br />

it explicit by using the keyword DEFAULT.<br />

INCLUDE Include user-missing values. PROBIT treats user-missing values as valid.<br />

Only cases with system-missing values are rejected.<br />

<strong>Reference</strong>s<br />

Finney, D. J. 1971. Probit analysis. Cambridge: Cambridge University Press.

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