Purpose

The Scale for Suicidal Ideation [SSI-4] aims primarily to assess and evaluate how frequently and to what extent individuals experience thoughts and desires related to committing suicide.

Key Characteristics

The Scale for Suicidal Ideation [SSI-4] was developed in the USA by Froyd and Perry (1985), following the model of the Los Angeles Suicide Prevention Center Assessment of Suicide Potentially. It includes four different types of questions, used to estimate the frequency and intensity of suicidal thoughts that “overwhelm” an individual. It was adapted from English to Greek by Kleftharas.

Scoring

The first three questions of the SSI-4 are related to the frequency of suicidal ideation in a person, assessed using a 5-point Likert scale, where a score of 1 means “never” and 5 means “all the time.”
The fourth question relates to the seriousness and strength of suicidal ideation and is assessed using a 4-point Likert scale, where a score of 1 equals “not at all serious” and 4 equals “there is a specific suicide plan.”
The total score is derived by summing the responses to the four questions, ranging between 4 and 19. Higher scores indicate a critical level of suicidal ideation.

Validity and Reliability

Regarding the reliability of the SSI-4, the Cronbach’s alpha coefficient was:
a = 0.95 for the total sample,
a = 0.81 for the community sample,
a = 0.95 for the outpatient population sample.
In addition, the scale shows internal consistency:
“Active suicidal desire” – α = 0.92
“Preparation” – α = 0.69
“Passive suicidal desire” – α = 0.79

References

Holi, M. M., Pelkonen, M., Karlsson, L., Kiviruusu, O., Ruuttu, T., Heilä, H., … & Marttunen, M. (2005). Psychometric properties and clinical utility of the Scale for Suicidal Ideation (SSI) in adolescents. BMC Psychiatry, 5(1), 1–8.