# Questionable necessity effects on suicidal ideation: a commentary on Marchetti et al. (2026)

## TL;DR

This paper challenges the conclusion that perceived burdensomeness and thwarted belonging are necessary for suicidal ideation, showing their effects could be due to correlations rather than necessity.

## Contribution

The paper introduces a method to assess the validity of necessity effects in NCA by estimating ranges of spuriousness.

## Key findings

- Necessity effects found by Marchetti et al. fell within the estimated ranges of spuriousness.
- The observed effects could be explained by correlations rather than true necessity.
- Researchers should require necessity effects to exceed spuriousness ranges to draw valid conclusions.

## Abstract

Marchetti et al. recommended researchers of mental health to use necessary condition analysis (NCA). In an empirical application, they found statistically significant necessity effects of perceived burdensomeness and thwarted belonging on suicidal ideation. However, necessity effects in NCA do not prove that X is necessary for Y, as the effect could, for example, be due to a correlation between X and Y and this correlation could, in turn, be due to a confounding impact by a third variable Z. We scrutinized the findings and conclusions by Marchetti et al. by estimating “ranges of spuriousness,” i.e., 95% confidence intervals of necessity effects that could be expected due to the correlations between suicidal ideation and perceived burdensomeness and thwarted belonging, respectively. The necessity effects fell within the range of spuriousness, meaning that they could be accounted for by the correlations between the variables. Hence, conclusions by Marchetti et al., that perceived burdensomeness and thwarted belonging are necessary for suicidal ideation, may be challenged. It is important for researchers using NCA to be aware of the method’s severe limitations. We recommend scrutinizing findings by estimating ranges of spuriousness and to require that necessity effects are above this range if concluding that X is necessary for Y.