Table 3 Criterion and construct validity of COVID-19 IPC Measures Survey (n = 627 actively working respondents)

Concurrent validity

There is a positive association between overall protective measures score and the ‘gold-standard’ question: Do you feel protected from COVID-19 at work?

583^a

Two-sample t-test^b

p < 0.001 ***

The survey instrument successfully measures the degree of COVID-19 safety a participant feels in the workplace.

Known-groups technique

The number of protective measures in place varies significantly by country

453^c

Two-sample t-test^bc

p = 0.04 *

The survey instrument successfully captures national differences in workplace protective response

Known-groups technique

The health care and social assistance sectors have more protective measures in place than other occupational sectors

627

Two-sample t-test^b

p < 0.001***

The survey instrument successfully captures occupational differences in workplace protective response

Discriminant validity

A participant in the highest protective scores quartile (i.e., whose workplace has more protective measures in place than 75% of survey respondents) is significantly more likely to feel protected at work than a participant in the lowest protective scores quartile

583 ^a

Univariable logistic regression^f

OR (95% CI) = 2.67 (1.17,2.95)***

Respondents with high IPC coverage are more likely to feel protected at work than those with low IPC coverage. The survey instrument is not improperly measuring the level of protection available to workers.

Discriminant validity

A participant in the lowest protective scores quartile (i.e., whose workplace has fewer protective measures in place than 75% of survey respondents) is significantly less likely to feel protected at work than a participant in the highest protective scores quartile

583 ^a

Univariable logistic regression^d

OR (95% CI) = 0.38 (0.23,0.62)***

Respondents with low IPC coverage are less likely to feel protected at work than those with high IPC coverage. The survey instrument is not improperly measuring the level of protection available to workers.