Sample
National samples both in Finland and the Netherlands were drawn from the respective consumer panels using online survey technology. Potential respondents were invited via email to complete the SARS questionnaire on the research companies’ website between June 19 and June 26 in 2003. A random sample (n = 500) was drawn from the pool of 10.000 members of an Internet-research panel in both countries (Taloustutkimus in Finland and Flycatcher in the Netherlands). The final Finnish sample consisted of 308 respondents (data gathering was finished after 300 had replied), and the Dutch sample of 373. Table 1 gives the background characteristics of the samples.
Table 1 Background characteristics of the respondents by country, Finns n = 308, the Dutch n = 373
Survey
The survey was based on the Psychosocial SARS Research Consortium study, extended by questions on the perceived risk of SARS, other infectious diseases, and some chronic diseases, efficacy beliefs—perception of one’s ability to control things such as SARS, and to prevent both SARS and infectious diseases in general (see Table 2 for the individual items). Leventhal et al.’s Illness Perceptions and Self-Regulation Models formed the psychological framework of the study [24, 25].
Table 2 Risk perceptions related to SARS and infectious diseases in general, differences between the distributions, Finns (n = 308) and the Dutch (n = 373) (unadjusted)
Knowledge of SARS was measured by 13 items (ever hearing of SARS, what SARS is, cause (etiology), mortality, symptoms, and treatment). The respondents were asked to tick the items they thought were correct, and a sum score (theoretical range 0–13, general reliability coefficient 0.65 [26]) was used for the descriptive analysis. The dimensions were divided into quartiles for the logistic regression analyses.
Risk perceptions. Subjects were asked to rate their personal risk of getting SARS (1 very low, 5 very high) and their comparative risk (compared to the risk of a person of the same gender and age living in the same country: 1 much lower–5 much higher). In addition, personal and comparative beliefs in the ability to prevent SARS and infectious diseases in general were probed (=efficacy beliefs).
Worry about one’s own risk of SARS, the family risk, and risk in the region were asked about using the scale: 1 not at all worried–5 very worried. The variables were re-coded so that 0 indicated no worry and 1 indicated at least some worry, and a sum score (theoretical range 0–3, reliability coefficient 0.73) was used for the descriptive analysis and the quartiles for the logistic regression analyses.
Precautionary behaviors were measured by 18 items, each tick bringing a numerical value of one, giving a theoretical range of 0–18, and a sum score (general reliability coefficient 0.72) was used in the analyses. The items were: avoidance of traveling to affected areas, eating in restaurants or food courts, shaking hands, travel on airplanes, taxis, trains or subways, avoiding going to gatherings, avoiding going to work or school, having worn a mask, having washed hands, having taken extra care of cleanliness, having used disinfectants, having eaten a balanced diet, exercise, taking herbal supplements, sleeping enough, and having done something else.
Diagnostic actions (taking one’s temperature, going to a doctor, paying close attention to coughing, sneezing, feelings of fatigue, headaches, and calling the SARS hotline) were measured by eight items similarly to the precautionary behaviors, and a sum score (theoretical range 0–8, general reliability coefficient 0.75) was used for the descriptive analysis and quartiles for logistic regression analyses.
SARS information sources and confidence in them were canvassed (see Table 3 for the items) using the response categories: 1 not at all/very little–5 very much. For the descriptive analysis, the answers were dichotomized so that the original values 1–3 were take to mean “little” and the values 4–5 “a lot.”
Table 3 Amount of SARS information received (n, %, little and much) from various sources, and confidence in the sources (n, %, little, much), Finns n = 308, the Dutch n = 373 (unadjusted)
Statistical Analyses
Distributions (frequencies, percentages) were used to describe the Finnish and Dutch samples, and chi-square tests (for dichotomous variables), and two-sided t-tests (continuous variables) were used to test differences between the samples on significant characteristics. Univariate logistic regression analyses were used to find significant differences (p < 0.05). Multivariate forward stepwise logistic regression analysis was used to compare the Finns with the Dutch. Odds ratios [with 95% confidence intervals (CI)] were calculated for levels of knowledge, perceptions, worry, behaviors, information sources, and trust (see Table 4).
Table 4 Multivariate forward stepwise logistic regression analysis: odd ratios (ORs, 95% confidence intervals) of different levels of SARS knowledge, worry, perceptions, behaviors, and information among Finns (n = 308) compared with the Dutch (n = 373), controlled for age, education, and income level
Variables significantly associated with the country (p < 0.05) in the univariate analysis were entered in a forward stepwise multiple logistic regression analysis in order of descending magnitude of the coefficient/SE, using a p value of ≤0.025 as the criterion [27] for the inclusion or exclusion of the variable. Since the samples differed in background factors such as age, educational level, and income level, the logistic regression analyses were adjusted for these variables. The analyses were done with the SURVO software [28]. P values less than or equal to 0.05 were considered statistically significant.