1. Temporal stability of self-reported driving behaviors
5th International Conference of Traffic and Transportation Psychology (Abstracts Book, pag. 94). Agosto 29-31, Groningen, Holanda.
Temporal stability of self-reported driving behaviors
Poó, Fernando M.1, Montes, Silvana A.1, and Ledesma Rubén D.1
1 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).
Grupo Modelos y Métodos de Investigación en Psicología del Tránsito. Facultad de Psicología. Universidad Nacional de Mar del Plata (Argentina).
Introduction
Reliability of driving self-report measures is usually assessed through internal consistency analysis. Other important and necessary analyses of reliability such as test-retest are little used. The present research examined the 6-month test-retest reliability for two self-report driving measures: the MDSI (Multidimensional Driving Style Inventory) and the ARDES (Attention-Related Driving Errors Scale).
Study 2. Test re-test reliability of the ARDES
The ARDES (Ledesma et al. 2010) is a self-report scale designed to assess individual differences in unintentional driving errors arising in whole or in part from failures of attention. In a previous work (Ledesma et al. 2010) the authors provide evidence of its scores validity and reliability. However, reliability was only assessed through internal consistency analysis. No results about test-retest reliability were provided until now. The aim of this study was to evaluate temporal stability of ARDES scores after a period of six months. It was expected a positive and strong test-retest correlation and the absence of significant mean differences.
METHOD
Participants
Data was gathered from a non-probabilistic sample of 65 drivers from the general population of the city of Mar del Plata (Argentina). Age range was 20 to 62 years old (Mean = 34.12; SD = 10.57). The sample had slightly more females (55 %) than males. Most participants drove almost daily (72%.3). Most participants (97 %) had an education attainment of at least high school
Measures
Driving errors were assessed by the ARDES. The ARDES is a Likert-type scale comprised of 19 items. The Cronbach’s Alpha for the scale in this study was .83 (test) and .80 (retest). Descriptive Statistics are shown in Table 1.
Study 1. Test re-test reliability of the MDSI
Driving style is the multidimensional pattern of behavior, attitudes and emotions that each driver displays on the road (Elander et al. 1993; Taubman – Ben-Ari et al. 2004). Even though it is assumed that driving style remain stable across time it has been usually assessed in cross sectional studies. The MDSI (Taubman – Ben-Ari et al. 2004) assesses the dimensions that compose driving style but the stability of its scores after a period of time has not been evaluated so far. The aim of this study was to evaluate temporal stability of driving style as it is assessed by the MDSI. We expected a positive and strong test-retest correlation and absence of mean differences between the two test times.
METHOD
Participants
The sample was composed of for 25 males and 25 females from the general population of the city of Mar del Plata (Argentina). Age range was from 19 to 74 years old (Mean = SD = 13.01).
Measures
A Spanish version of the MDSI (Ledesma et al. 2008) was administered. The inventory assesses the following dimension: (1) risky driving (2) dissociative driving, (3) angry driving. (4) anxious driving, and (5) careful driving style. Items ask about driver behaviors, attitudes and emotions in a six point Likert scale (ranging from 1= nothing, to 6 = very much).
Procedure
Researchers contacted prospective participants on an individual basis. All prospective participants approached consented to participating in the study. The questionnaire was re-administered six-months later. Data were treated confidentially.
RESULTS
The diagonal in Table 2 displays test-retest correlations among scales. The rest of the table presents correlations among scales in each time (test and retest).
No mean differences were observed for risky, t(46) = , p = .153; dissociative, t (45)= , p = .117; angry t(48)= 0.936, p = 0.354; or careful driving styles t(43) = 0.983, p = However, mean differences were observed for the anxious driving style t(46)= 2.69, p = .01. Nevertheless, after a repeated measures ANOVA controlling for driving experience the difference dissapeared F(1.45) = 3.85, p > .05.
Table 1. Mean and Standard Deviation for ARDES
Administration
ARDES
Mean SD
Test
28.95
6.35
Retest
30.43
5.93
Procedure
Researchers contacted participants via and invited them to answer an on-line questionnaire. The same invitations were sent six months later. Before answer the questionnaire all participants gave their informed consent. Data were treated confidentially
Data analysis included Pearson’s r to analyze correlation test-retest and Student’s t to test mean differences.
RESULTS
Test-retest correlation was positive and strong (r= .80. p< .001). Mean differences were observed between first and second administration t (64) = p=.003. d = -.24.
DISCUSSION
Test-retest correlation was highly satisfactory according to Cronbach (1970). Contrary to our expectations, we found significant differences between means, although according to the effect size the magnitude of the difference was low. Thus, this study gives positive evidence about the test-re-test reliability of the ARDES’s scores. Also, it supports the conceptualization of driver inattention as a relatively stable pattern of behavior across time.
Table 1. Descriptives for the MDSI’s scales.
MDSI’s Scales
Risky
Angry
Anxious
Dissociative
Careful M SD
Test
2.08
1.03
2.69
0.95
2.14
0.80
1.8
0.50
4.44
0.83
Re-test
2.18
1.1
2.64
0.87
1.95
0.7
1.9
0.63
4.33
0.81
Table 2. Pearson correlations for the MDSI scales in the moments 1 and 2
MDSI Scales
Risky
Dissociative
Test/ReTest
Angry
Anxious
Careful
.93 **
-.07/.12
.62**/.62**
-.16/-.07
-.49**/-.50 **
.83 **
.04/.10
.34**/.35*
-.03/-.19
.89 **
-.06/-.02
-.32*/-.46**
.79 **
.28/ .10
.71 **
CONCLUSION
Both studies provide new evidence of reliability for the scores of two different instrument that evaluate driver behavior and also provide support to the conceptualization of the temporal stability of behavior on the road. Longitudinal studies which include longer time intervals between testing times are needed.
DISCUSSION
Cronbach (1970) argued that correlations between scales after a period of one month are acceptable if surpased a value of .69. According to this assertion, results found in this study were highly satisfatory. Despite mean differences were observed for anxious driving driving style (see Table 1), the decrease observed in the mean could be regarded as a consequence of novel drivers’ habituation to traffic. Anxiety in novel drivers usually decline after the first few months of driving alongside with the acquisition of new skills. Results from this study supports the hypothesis of the stability of driving style and also give new evidence of reliability for the MDSI as a specific measure of driving style.
References
Cronbach. L.J. (1970). Essentials of Psychological testing. Nueva York: MacMilla
Elander. J.. West. R.. & French. D. (1993). Behavioral correlates of individual differences in road traffic crash risk: an examination of methods and findings. Psychological Bulletin
Ledesma, R., Peltzer, Poó, F. & López de Cozar, E. (2008). Fiabilidad y validez del inventario multidimensional de estilos de conducción (MDSI) adaptado para la población argentina. V Congreso de Metodología de Encuestas. Córdoba, España de septiembre de 2008.
Ledesma. R.. Montes. S.. Poó. F.. & López-Ramón. F. (2010). Individual Differences in Driver Inattention: TheAttention-Related Driving Errors Scale. Traffic Injury Prevention
Taubman - Ben-Ari. O.. Mikulincer. M. & Gillath. O. (2004). The multidimensional driving style inventory-scale construct and validation. Accident Analysis and Prevention –332.