The sdt
Module¶
d_prime |
Calculate the sensitivity index d’. |
a_prime |
Calculate the sensitivity index A’. |
criterion |
Calculate the decision criterion C. |
Signal detection theory calculations.
-
pphelper.sdt.
a_prime
(hits, false_alarms, n, nafc=1)¶ Calculate the sensitivity index A’.
Parameters: - hits (float) – The number of hits when detecting a signal.
- false_alarms (float) – The number of false alarms.
- n (int) – The number of trials in target and no-target trials.
- nafc (int, optional) – The number of alternative choices in the task. A value of
1
implies a Yes/No task. Defaults to 1.
Returns: A – The calculated A’.
Return type: float
Example
>>> from pphelper import sdt >>> sdt.A_prime(20, 10, 25) 0.79166666666666674
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pphelper.sdt.
criterion
(hits, false_alarms, n, nafc=1)¶ Calculate the decision criterion C.
Parameters: - hits (float) – The number of hits when detecting a signal.
- false_alarms (float) – The number of false alarms.
- n (int) – The number of trials in target and no-target trials.
- nafc (int, optional) – The number of alternative choices in the task. A value of
1
implies a Yes/No task. Defaults to 1.
Returns: C – The decision criterion. This will be zero for an unbiased observer, and non-zero otherwise. In a 1-AFC (Yes/No) task, a value smaller than 0 implies a bias to responding “Yes”, and a value greater than 0 a bias to responding “No”.
Return type: float
Example
>>> from pphelper import sdt >>> sdt.criterion(20, 10, 25) -0.29413706521855731
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pphelper.sdt.
d_prime
(hits, false_alarms, n, nafc=1)¶ Calculate the sensitivity index d’.
Parameters: - hits (float) – The number of hits when detecting a signal.
- false_alarms (float) – The number of false alarms.
- n (int) – The number of trials in target and no-target trials.
- nafc (int, optional) – The number of alternative choices in the task. A value of
1
implies a Yes/No task. Defaults to 1.
Returns: d – The calculated d’ value, z(hit_rate) - z(fa_rate).
Return type: float
Example
>>> from pphelper import sdt >>> sdt.d_prime(20, 10, 25) 1.094968336708714