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Questions tagged [d-prime]

d' (also called sensitivity index) is a measure used in signal detection theory to quantify how well a signal can be distinguished from noise.

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15 votes
2 answers
27k views

d prime with 100% hit rate probability and 0% false alarm probability

I would like to calculate d prime for a memory task that involves detecting old and new items. The problem I have is that some of the subjects have hit rate of 1 and/or false alarm rate of 0, which ...
A.Rainer's user avatar
  • 257
13 votes
1 answer
4k views

Connections between $d^\prime$ (d-prime) and AUC (Area Under the ROC Curve); underlying assumptions

In machine learning we may use the area under the ROC curve (often abbreviated AUC, or AUROC) to summarise how well a system can discriminate between two categories. In signal detection theory often ...
Dan Stowell's user avatar
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7 votes
1 answer
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Why use d-prime instead of percent correct?

In signal detection theory, people often use $d'$ to assess performance. Apart from the fact that $d'$ is in $z$ units (units of measurement transformed to standard deviation units, i.e., $z$ scores), ...
user41270's user avatar
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6 votes
1 answer
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Are Cohen's d (effect size) and d prime from the signal detection theory measuring the same thing?

Are d prime (d') in signal detection theory and Cohen's d (mainly reported in the context of the general linear model) measures for the same thing (i.e., the difference of the means in SD-units), and ...
Sebastian Horn's user avatar
3 votes
0 answers
890 views

A' (A prime) for extreme Hit rates and False Alarms

I am trying to compute the non parametric measure of sensitivity A' according to the following formula reported by Stanislav & Todorov (1999): $$ A'= .5+sign(H-F)*((H-F)^2+abs(H-F))/(4*max(H,F)-4*...
Elio Balestrieri's user avatar
2 votes
2 answers
2k views

How do I calculate d' from experimental data?

In Signal Detection Theory, d' is defined by the z-scores of Hits and False Alarms: d' = z(Hits) - z(False Alarms). Say the task is to detect if a certain object is present in a series of pictures, ...
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1 vote
0 answers
36 views

Can Splithalf Reliability Be Caclulated for an Aggregate Measure?

I have been asked by a journal editor to provide the splithalf reliability for an aggregate dependent variable, d', which is a Signal Detection parameter that captures perceptual sensitivity. However, ...
Shannon's user avatar
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1 vote
0 answers
258 views

ROC curve, d' A' - assumption-free?

In my research I want to know how reliably certain feature of a sentence indicates the class that sentence belongs to. So, according to that feature (=how many elements X they contain), the ...
Leandra's user avatar
  • 63
1 vote
0 answers
248 views

d prime correction to use with a low number of trials

I am doing a psycholinguistic experiment, where I want to calculate d’ for each participant’s test scores. In the test, participants listen to 4 familiar words and 8 novel distractor words, and have ...
Theresa's user avatar
  • 11
1 vote
1 answer
659 views

Is there an accepted way to interpret d' (d-prime) for evidence of detection

I have run a learning experiment, with a yes-no familiarity test at the end, and computed d' across various conditions. Is there some rule of thumb (perhaps dependent on sample size) as to how d' ...
Henry Brice's user avatar
1 vote
0 answers
1k views

Negative D-prime values; use absolute values?

I have calculated D-prime measurements for for a memory performance task. Subjects viewed images that were either old or new and had to indicate their response via a button press. Thus, their response ...
Inkling's user avatar
  • 299
0 votes
1 answer
2k views

Understanding and implementing the dprime measure in Python

According to Wikipedia, the dprime score (aka 'sensitivity index') can be expressed as $$ d' = Z(\text{hit rate}) - Z(\text{false alarm rate})$$ hit rate (aka recall aka sensitivity) and false alarm ...
andandandand's user avatar