The current article reports data from three Polish samples to examine the Relationship Assessment Scale (RAS) with respect to its unidimensionality, invariance across countries, gender, formal and informal relationships, degree of precision (or information) across latent levels of relationship satisfaction, and the functioning of individual items. The analyses of the data from the reference sample (n = 733) confirmed a clear 1-factor structure of the RAS-PL and good internal consistency. Configural, metric, and scalar invariance for countries (Poland, Hungary, USA), gender (women and men) and relationship types (formal and informal relationships) were achieved. Item Response Theory Analysis (IRT) suggested that the RAS-PL assesses relationship satisfaction most reliably at low to average levels. Analyses of the data from validation samples (n = 203 and n = 209) confirmed the convergent and divergent validity by weak, medium, and large correlations of the RAS-PL with measures of other theoretically related constructs. Concurrent criterion validity was demonstrated by a strong positive correlation between the RAS-PL and the intent to continue the current relationship. This investigation provides considerable psychometric information about the items and scale of the RAS-PL.

"The scientific need to recognize the impact of the COVID-19 pandemic on human psychosocial functioning requires reliable and valid research tools to assess this impact. Therefore, we designed a study to create and further validate a Polish version of a research instrument assessing stress, anxiety, and fear related to the pandemic – the COVID Stress Scales (CSS; Taylor et al., 2020). This paper presents the specific research steps designed to develop and validate the Polish-language version of CSS (Taylor et al., 2020). These steps are as follows: 1) the translation of the original CSS into the Polish language by three independent translators and the back-translation by three other independent translators; 2) the assessment of the equivalence of the Polish translation of CSS in a study involving a sample of 30-60 bilingual people, fluent both in English and Polish languages; 3) the pilot study employing the pre-final Polish version of CSS; 4) the validation study involving a sample 600-900 participants in which the following instruments will be used: the Fear of COVID-19 Scale, the Patient Health Questionnaire-9 Scale, the Short Health Anxiety Inventory, the Social Desirability Scale, the Obsessive-Compulsive Inventory-Revised Scale, the Xenophobia subscale of the Questionnaire of Political Beliefs and the subscale Sensation seeking from the Impulsive Behavior Scale. We expect that the Polish version of CSS will be widely used by Polish researchers in their studies concerning the impact of the COVID-19 pandemic and other epidemiological threats on mental health. At the same time, we hope that our study will provide results that will help foreign researchers understand the COVID-19 pandemic in other countries."