The Road Ahead



Effect Size
Clinical Change
Odds Ratio
Random Nos


Brain At Work


We are also making available free software which compute simple statistics or more complex psychometric results using popular questionnaires. We have tried to focus on instruments where the original questionnaire has been made freely available by the authors!!

Equivalence Generator Computes a Two One-Sided t-Test (TOST) for independent and paired samples. This allows us to test for equivalence as opposed to difference (although this programme does both).
DASS 21 Scoring & Interpretation Generator The Depression Anxiety Stress Scales (DASS; Lovibond & Lovibond, 1995) is a freely available psychometric test assessing Depression, Anxiety and Stress. There is a 42 item and 21 item version of this instrument. This programme below will score and provide interpretive guidelines for the 21 item version.
PTSD Scoring & Interpretation Generator The PTSD Checklist is a 17 item trauma symptom severity checklist. This second version programme computes scores and interprets according to both 'research rules' and 'DSM-IV rules'.
BDI Scoring & Interpretation Generator The Beck Depression Inventory in a 21 item measure of depressive symptomatology. This scorer will provide z scores, percentiles and a category rating of the derived score.
Very Average Generator This small application computes averages for up to 6 numbers using both unweighted and weighted formulae.
Standard Deviation Generator This application will allow you to convert the standard error of the mean into a standard deviation and also allow you to compute the standard deviation from a given confidence interval (e.g., 95% confidence intervals).
Z-Score & Percentile Generator This application computes Z-scores and percentiles for a mean and standard deviation (SD). It will also convert between an SD and a confidence interval and convert between a confidence interval and a SD. It will also compute whether a score is significantly different from a scale's mean (e.g., whether a score on a questionnaire is significantly different from the mean).
Prediction Rate Success Generator This programme computes the likely number of true hits one would get by chance if one randomly allocated individuals to one of two groups. It is useful to compare your success rate compared to that of chance.
d' (d Prime) Generator Inspired by Prof Jeff Lohr, this programme computes two types of d'. In the first version (where no base rates are known), d' is the standardised difference between a true signal and an untrue signal (i.e., noise). The second version of d' computes probabilities of a condition given the hits (true signals), false alarms (untrue signals; i.e., noise), and base rates (how prevalent is the condition).


More to come ...



Beck, A.T., Ward, C. H., Mendelson, M., Mock, J., && Erbaugh, J. (1961). An inventory for measuring depression. Archives of General Psychiatry, 4, 561-571.

Lovibond, S.H., & Lovibond, P.F. (1995). Manual for the Depression Anxiety Stress Scales (2nd Ed.). Sydney, Australia: Psychology Foundation of Australia.

Weathers F, Huska J, and Keane T. (1991). The PTSD Checklist Military Version (PCL-M). Boston, Mass: National Center for PTSD.



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Copyright 2005 Psytek Ltd. Last modified: 02/02/17 05:22:06 PM