Randomized Control Trial of an Intervention to Increase Perceived Safety Benefit of Booster Seats Among Parents of Children 4 to 8 Years Old in Canada.
Phase: NA
Conditions: Wounds and Injuries
Sponsor: University of British Columbia

 
 
 
 
University of British Columbia 
Randomized Control 
Trial of Booster Seat 
Education Material 
to Increase 
Perceived Benefit 
Among Parents 
NCT: 03573830 
6-27-2019 
 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
COMMUNICATING THE SAFETY BENEFIT OF BOOSTER SEATS 
Overview  
Seatbelts protect people from injuries, by diverting crash forces to stronger anatomical 
structures: the ribcage and the pelvis.1 Children between the ages of 4 and 8 years are typically 
not tall or heavy enough to wear the seatbelt correctly across the chest and hips, and instead 
wear it on their abdomen and neck (Figure 1, left). When worn in this way, seatbelts direct crash  
forces to these parts of the body causing 
serious damage to internal organs and even 
severing the spine.2–4  For this reason, children 
of these ages need to use a booster seat. A 
booster seat is a safety device that prevents 
seatbelt related injuries, by raising the child and 
ensuring the straps are correctly worn across 
the thorax and hips (Figure 1, right). 
Unfortunately, in Canada, half of the children 
who should be using booster seats are 
prematurely restrained using only the seatbelt.5 
 
Figure 1. Left: premature use of seatbelt. Right: correct 
use of seatbelt in combination with booster seat 
The present research project seeks to develop a new way to encourage booster seat use. 
Research on booster seat use demands urgent financial support for four reasons: (1) 
Canadian children today are at higher risk of sustaining motor vehicle collision injuries, because 
they are spending more time in cars than a decade ago.6 (2) The potential physical and 
emotional consequences of premature use of seatbelts can be devastating for children and 
families, because its associated injuries often lead to permanent paraplegia and, sometimes, 
death.2,4,7 (3) Canada must capitalize on the political momentum created by the United Nations’ 
Decade of Action for Road Safety.8 As a participant country, our nation committed to significantly 
increase child restraint use during the years 2011 through 2020. In other words, we only have 
three years left to conduct more research and translate it into policies and programs.9,10 Finally 
(4) given that premature use of seatbelt is a modifiable risk factor and is prevalent among half 
the population, the development and implementation of interventions to promote booster seat 
use is not just desirable; is imperative. 
Canada has made notable progress in the promotion of booster seat use. Specifically, 
Canada’s automobile research program has produced new booster seats that are easy to carry 
and install, as well as attractive to school age children.11 Furthermore, nine provinces have now 
enacted laws mandating booster seat use,12 and evidence-based education programs have 
been developed and implemented throughout the country.13–15 Despite these advances, new 
approaches to encourage booster seat use are required, because legislation has proven 
insufficient to effectively promote booster seat use.16–18 For example, in 2010, more than 10 
years after booster seats became mandatory in Ontario and Quebec, the rate of utilization in 
each of the two provinces was only 25%.5 Furthermore, recent research indicates that parents’ 
perception of the safety benefit of boosters seats is the single, strongest predictor of use,19,20 yet 
no study to date has tested an education intervention that increases perceived benefit.21–34 
Instead, studies conducted to date focus on teaching guidelines (i.e., minimum and maximum 
age, height, and weight to determine when a child should use a booster seat, and when it is safe 
for a child to use only the seatbelt). 
My approach to encouraging booster seat use is novel, because I propose that, in addition to 
learning guidelines, parents need to understand two principles: (1) seatbelts prevent injuries by 
redirecting crash forces to stronger parts of the body (hips and chest); and (2), without booster 
seats, children would wear the seatbelt on their abdomen and neck, which directs crash forces 
to more vulnerable anatomical structures (internal organs and spine). Once parents grasp these 
two principles, they will appreciate the safety benefit of booster seats and, thus, will be more 
likely to use them. 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
Background 
Motor Vehicle Collisions are the leading cause of unintentional injury death for Canadians 
between the ages of 1 to 14 years.35 Injuries to underage vehicle occupants are the leading 
cause of mortality and second cause of hospitalization.36 Compared to other age groups, child 
occupants aged 4 to 8 years are at higher risk of motor vehicle injury because approximately 
half of them are prematurely restrained in seatbelts, which provide less than optimal protection. 
In effect, using a booster seat in combination with a seatbelt reduces the risk of injury during a 
collision by an average of 45%, considering all crash directions, and by 68% and 82% in near- 
and far-side impact crashes, respectively.37 
Previous efforts to increase booster seat use in Canada and reduce premature use of 
seatbelt have led to significant advances. One study, which involved direct observation of 
children inside cars at randomly selected intersections across country, found that the proportion 
of parents who forgo the use of booster seats and prematurely restrain their children in adult 
seatbelts decreased from 63% in 2006 to 50% in 2010.5 More recently, province-wide surveys 
show that rates of booster seat use have reached 77% and 95%, in Alberta and Nova Scotia 
respectively. However, it is important to note that these figures are likely inflated, because the 
methods used (parking lot surveys and self-report) are susceptible to self-selection and self-
report bias. 
In Canada, interventions to promote booster seat use fall in at least one of three categories 
known as the Three E’s of Injury Prevention38: engineering, enforcement, and education. 
Engineering interventions have developed booster seats that are portable, easy to install, and 
attractive to more mature children. The Clek, for example, is an award-winning booster seat 
developed within Canada’s automotive research program, and funded by NSERC and the 
automobile industry.11Enforcement interventions involve enacting legislation mandating the use 
of booster seats. In this area, Canada has also seen progress: in 2005, only two provinces had 
legislation mandating use of booster seats.16 However, today booster seat laws are in place in 
most jurisdictions, except the province of Alberta and the territories.12 Lastly, education 
interventions constitute the bulk of prevention efforts to promote booster seat use, and 
frequently target parents’ behaviours. National organizations dedicated to educating parents 
include Transport Canada (which provides online information for parents), Parachute (a charity 
organization dedicated to reducing the burden of injuries in Canada), and the Child Passenger 
Safety Association of Canada, an organization that certifies and supports child seat educators 
from all provinces. At the provincial level, private and public organizations like the Automobile 
Association of BC and Saskatchewan Government Insurance, offer car seat clinics, where 
parents are given hands-on training on booster seat use. Most of these education interventions 
follow evidence-based practice; that is, they combine booster seat distribution programs with 
education on guidelines.14 
 
Why the new approach is necessary 
As Canada progresses in the promotion of booster seat use, researchers and practitioners 
recognize that more advances can be readily made, particularly given the success in promoting 
the use of other child restraints. While booster seat use is only 37% nationally, utilization rates 
of other types of car seats are estimated at 90% for children one year old or younger, and 80% 
for children between 1 and 4 years.5 Furthermore, while most Canadian provinces have adopted 
a booster seat law, legislation has shown a modest effect in the absence of education. An 
ecological study comparing rates of booster seat use across provinces with and without 
legislation showed that booster seat laws increase use, but this effect is limited in the absence 
of campaigns to inform the public about these devices and the law itself.17 A study that 
compared rates of booster seat use in Nova Scotia before and after legislation reached a similar 
conclusion.18 Finally, a cross-sectional study with 1,700 parents from provinces with and without 
legislation found that the best motivator for booster seat use is parents’ perceived safety benefit 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
(i.e., an understanding of the injury risk reduction afforded by booster seats in case of a 
crash).19 This finding was replicated in a second study with 1,500 parents across Canada.20 
It follows, then, that educating parents on the safety benefit of booster seat is necessary to 
increase the effect of legislation. Nevertheless, current education interventions rarely include 
strategies to directly address parents’ perceptions of the safety benefit of booster seats. Indeed, 
all 14 published and unpublished education interventions documented since 1987 involve 
education on guidelines (i.e., minimum and maximum age, height, and weight to determine 
when a child should use a booster seat, and when it is safe for a child to use only the 
seatbelt).21–34 Out of those, five address benefit or importance without explicitly mentioning 
safety benefit;21,25,28–30 three include a description of the potential injuries prevented by booster 
seats;21,24,34 and only one describes in detail the safety benefit of booster seats (i.e., explains 
how booster seats ensure crash forces are redirected to the hips and chest).39 Furthermore, 
none of these interventions include perceived safety benefit as an intermediate outcome 
measure, and instead focus on knowledge of guidelines,21,22,31 support for booster seat law,22,31 
and reasons for not using or purchasing a booster seat.31,32 
In summary, Canada has seen important advances in the promotion of booster seat use, in 
the past decade: engineers have developed booster seats that accommodate the needs and 
expectations of Canadian parents; legislation is in place in most jurisdictions; and evidence-
based education programs have been implemented in most provinces. Despite these advances, 
more can be done to further increase booster seat use in Canada. Cross-sectional studies 
suggest that booster seat legislation should be complemented with education interventions that 
increase parents’ perceived safety benefit of booster seats. However, no education intervention 
study to date has explicitly used perceived safety benefit as the main vehicle to encourage use. 
 
Theoretical framework: how to increase perceived safety benefit of boosters seats 
The proposed approach to educate parents on booster seat use was inspired by fuzzy-trace 
theory (FTT), a psychological model of decision making with applications in health.40 FTT 
postulates that people often make health decisions based on stereotypes of medical conditions 
(e.g., “cancer are tumours,” “sexually transmitted infections are fluid-borne”). Drawing upon this 
tenet, I hypothesize that many parents do not use booster seats because they tend to see 
injuries to vehicle occupants as resulting from ejection, and thus, are more concerned about the 
child being thrown through the windshield. This fixation on ejection takes parents’ attention 
away from the dangers of early and incorrect use of seatbelts. The resulting thought process 
may be characterized as follows: “injuries to children riding in cars are ejection related; seatbelts 
prevent ejection; therefore, seatbelts alone are safe enough (i.e., booster seats are not 
needed).” Indeed, research on parental attitudes and knowledge about booster seats indicates 
that parents believe that seatbelts provide enough protection.32,41,42 I have termed this 
misconception, the ejection stereotype. 
Preliminary evidence for the ejection stereotype was obtained through an online 
psychological experiment with 312 child seat technicians, researchers, and professionals in 
child passenger safety. Participants had varying degrees of experience (from 0 to 39 years) and 
knowledge of guidelines (from 0 to 100% scores in a 9-item questionnaire). Child seat 
technicians, researchers, and professionals were used in this study, to examine the role of 
knowledge and experience in the ejection stereotype: if knowledge or experience attenuate the 
ejection stereotype, then participants with more experience or knowledge would be less 
susceptible to it. 
This preliminary study used a pretest-posttest design, where experts’ judgments of the safety 
benefit of booster seats were compared across 2 conditions: (1) At the beginning of the survey, 
participants were asked to rate from 0 to 100% how much booster seats, used in combination 
with seatbelts, reduce the risk of injury. (2) At the end of the survey, participants were asked the 
same question with a small modification: this time non-ejection injuries were made salient by 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
listing all injuries that a child passenger can sustain, including those caused by premature use 
of seatbelts (see Figure 2). 14 questions on attitudes and knowledge were placed between 
conditions 1 and 2 to reduce the influence of the first question on the next. A participant was 
considered to have the ejection stereotype, if his or her ratings of the injury risk reduction were 
higher in condition 2 than in condition 1. 
Condition 1: Compared to seat belts alone, the combination of booster seat and 
seatbelt, used as shown in the picture, is ____% effective in reducing the risk of injury. 
Condition 2: Compared to seat belts alone, the combination of booster seat and 
seatbelt, used as shown in the picture, is ____% effective in reducing the risk of 
injuries to the head, neck, spine, abdomen, internal organs, as well as injuries 
resulting from ejection. 
Figure 2. Pretest-Posttest study on experts’ perceived benefit of booster seats. Condition 1 was presented at the 
beginning of the online survey and Condition 2 at the end. 
A Wilcoxon Sign and Rank Test indicated that, indeed, experts’ ratings of the injury risk 
reduction afforded by booster seats were significantly higher in Condition 2 than in Condition 1 
(Z = 3.157; p = 0.002). Moreover, multiple linear regressions showed that this difference was not 
associated with participants’ knowledge of guidelines and experience, even though, the study 
had 96% chance of detecting a very small effect (R2 = 0.05). 
 
Study rationale and hypothesis 
Drawing from the aforementioned theory and preliminary findings, I hypothesize that the 
perceived safety benefit of booster seats can be increased by eliminating the ejection 
stereotype. More specifically, I postulate that people become aware of the additional injury risk 
reduction afforded by booster seats, after they learn that: (a) seatbelts redirect crash forces to 
the child’s thorax and pelvis; (b) booster seats ensure children wear the seatbelt correctly 
across the hips and chest; and (c) booster seats, used in combination with seatbelts, prevent 
injuries to head, neck, spine, abdomen, internal organs, as well as injuries resulting from 
ejection. 
To examine this hypothesis, I have formulated a research project comprising two parts: (1) a 
development phase, where I will produce a new booster seat education material designed to 
increase perceived benefit of booster seats; and (2) a Phase II proof-of-concept randomized 
controlled trial, where the effects of the new education material on perceived safety benefit and, 
ultimately, intention to use will be tested in controlled conditions. 
 
Research Plan and Methods 
Development phase 
Objective. To develop booster seat education material that corrects the ejection stereotype. 
Participants. Twelve mothers and twelve fathers of children 4 to 8 years old, residing in the 
Greater Vancouver area, who speak English and drive with their children at least once a month. 
I chose this cut-off point, because use of all types of child seats (including booster seats) has 
been reported to be lower among families that drive their children less than once a week 
compared to more than once per week.43 Participants will be excluded if their child has a 
physical condition that requires special transportation arrangements. Parents will be invited to 
participate, irrespective of whether they use booster seats always, occasionally, or never. This 
will not affect the scientific value of the focus group interviews, because the intervention is 
intended to increase perceived safety benefit, irrespective of the current habits around booster 
seats. I hypothesize that even parents who consistently restrain their children on booster seats 
will exhibit the ejection stereotype (e.g.,  some parents may be using booster seats, because it 
is mandated by law, not because they understand its safety benefit). Participants will receive 
$40/each for taking part in the focus group. 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
Recruitment. Participant recruitment will take advantage of a large scale study with parents of 
school-aged children, led by the applicants’ graduate supervisor, Dr. Mariana Brussoni. 
Participants for both studies will be recruited through Facebook and snowball methods. In this 
way, the present study will have the support of a recruiting team comprising four research 
assistants and a full-time research manager. 
Procedure. The new booster seat information material will be created by taking Transport 
Canada’s44 online material (click here to open link) and then by adding an introduction that 
explains: (a) seatbelts redirect crash forces to the child’s thorax and pelvis; (b) booster seats 
ensure children wear the seatbelt correctly across the hips and chest; and (c) booster seats, 
used in combination with the seatbelts, prevent injuries to head, neck, spine, abdomen, internal 
organs, as well as injuries resulting from ejection. See Appendix 1. Three focus group interviews 
(one with fathers only, one with mothers, and one mixed) will be conducted to test the enhanced 
material. Focus group discussions will revolve around knowledge and beliefs about booster 
seats and seatbelts, as well as opinions regarding the content, wording, and format of the 
education material. 
 
Analysis. The focus group interviews will be audio recorded and participants’ feedback will be 
used to improve the material’s concept (i.e., whether the message produced the intended effect) 
and execution (i.e., whether the material effectively conveys the intended message), as 
appropriate. 
 
Randomized Controlled Trial 
Objective. To determine if the enhanced Transport Canada online material is better than the 
current version at increasing perceived safety benefit and intention to use booster seats. 
 
Design. An internet-based Phase II proof-of-concept trial (with a control group) will be 
conducted, in order to test if the intervention produces the intended psychological effect. The 
trial will use a concurrent two-group parallel randomized controlled design. The use of a control 
group is necessary to address threats to validity stemming from repeating observations on the 
same participants: learning and carry-over (i.e., learning something in the first question that then 
informs subsequent answers), sensitization (i.e., becoming more sensitive to differences by 
subsequent questions), and demand effects (i.e., noticing that the researcher wants a different 
response in the second question). 
 
Randomization. Randomization schedule will be generated using the sealedenvelop.com. 
Randomization will be stratified by province, gender, and socioeconomic status. Additionally, 
randomization will be blocked to ensure balanced groups throughout allocation. 
 
Blinding. Both researchers and participants will be blinded to allocation, even during data 
analysis. 
 
Intervention. The intervention will be the enhanced Transport Canada booster seat material that 
was developed in the previous phase. The intervention material will be the same as the one for 
the control group in all respects (font size, formatting, etc.), except that it will contain an 
introduction explaining, in plain language: (a) seatbelts redirect crash forces to the child’s thorax 
and pelvis; (b) booster seats ensure children wear the seatbelt correctly across the hips and 
chest; and (c) booster seats, used in combination with the seatbelts, prevent injuries to head, 
neck, spine, abdomen, internal organs, as well as injuries resulting from ejection. The final 
version of these introduction and accompanying figures will be decided, based on input from the 
focus groups.  

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
Outcome measures. The primary outcome measures are perceived safety benefit of booster 
seats and intention to use them, as assessed by the Booster Seat Attitudes Scale (BSAS).20 
The BSAS has been validated and tested in a Canadian sample of parents, and the Benefit and 
Intent subscales of the BSAS reported good internal consistency (Cronbach’s alpha of 0.85 and 
0.84, respectively). Secondary outcome measures are information recall (when it is safe to start 
using a booster seat, how to install it, how to use it, and when it is safe for a child to use only the 
seatbelt) and self-efficacy (as measured by the Perceived behavioural control subscale of the 
BSAS; Cronbach’s alpha of 0.87), their subjective estimates of the risk reduction afforded by 
booster seats (from 0 to 100%), their subjective estimate of the impact of the intervention on 
other parents, time they spend reading the material, clicks on links to additional booster seat 
information. 
 
UPDATE 27 OF JUNE 2019: Factor validation of the BSAS revealed that using the Benefit 
subscale actually comprises Perceived Benefit (i.e., understanding that booster seats prevent 
injuries) and Key Benefit (i.e., understanding that booster seats prevent life threatening injuries 
to the spine and abdomen). Similarly, the Intent subscale of the BSAS was found to have 
factors: Intent to Use and Intent to Learn (i.e., intention to attend a car seat clinic or workshop). 
The projected intent scale, developed for this study also had two factors: Projected intent to use 
and projected intent to learn. These new subscales constitute the updated outcome measures. 
 
Participants. 303 mothers and 303 fathers of children 4 to 8 years old residing in any Canadian 
province, who speak English and drive with their child at least once a month. Participants will be 
excluded if their child has a physical condition that requires special transportation. Parents will 
be invited to participate, irrespective of whether they use booster seats always, occasionally, or 
never. A sample of 606 participants provides sufficient power to detect a mean difference of 0.4 
points in the Benefit subscale of the BSAS. This difference in benefit scores has been found to 
distinguish those parents who consistently restrain their child in booster seats from those who 
do not. Sample size was estimated with the TwoSampleMean function for trials that test 
superiority of interventions (TrialSize package for R). Participants in the trial will receive $1/each 
for the completion of the survey. Based on information from studies with similar characteristics, 
the expected response rate is 40%. 
 
Setting and Procedures. The trial will be conducted entirely online. The online trial will be pilot-
tested with a sample of 10 parents, recruited through the same procedure used for the focus 
groups. Each participant will be asked to complete the online trial, in the presence of a 
researcher, at their home, office, or the researcher’s lab located in the BC Children’s Hospital. 
Each participant will be asked to speak out loud as he or she navigates the online trial. The 
researcher will ask probing questions if participants understand the question in an unintended 
way, do not understand what they are supposed to do, move the mouse erratically, or express 
frustration and/or confusion. Participants will then be debriefed to identify any potential 
misunderstanding of the information provided (e.g., incorrectly inferring that seatbelts are 
inherently dangerous for children rather than necessary safety devices that must be used in 
combination with booster seats). At the end of the pilot test, participants will receive $40/each. 
The online questionnaire and education material will be improved or corrected, as appropriate. 
After pilot-testing is complete, participants will be recruited through an online market research 
firm, Maru/Matchbox, which maintains a nationwide panel of 130,000 individuals whose 
distribution represents the Canadian population. Maru/Matchbox will send an email invitation to 
participate along with a link to the online survey. The landing page of the survey will provide 
description of the study for parents to read. The online survey will be set up in such a way that 
participants won’t be able to start answering questions, unless they consent by clicking the “I 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
agree” button. Participants, will be advised to print and keep a copy of the consent form either 
as PDF or as hard copy. After consenting to participate, the online trial will proceed as follows: 
1. Participants will complete a demographics questionnaire, the BSAS, and four questions on 
booster seat guidelines (e.g., minimum and maximum ages, heights, and weights to 
determine when a child should use a booster seat, and when it is safe for a child to use only 
the seatbelt). 
2. The system will randomly assign the participant to either the intervention or the control 
group. Randomization will be stratified by sex, child age, and jurisdiction to ensure both 
groups are equal. This stratification is necessary because, in Canada: (a) fathers and 
mothers differ in their attitudes regarding child vehicle safety,45 (b) booster seat use 
decreases as the child gets older,46 and (c) provinces differ from one another in terms of 
legislation and booster seat education programs.47 
3. Participants in the intervention group will be presented the enhanced booster seat material, 
while participants in the control group will be presented the current Transport Canada 
booster seat material. Material provided to both groups will be stripped of logos (Transport 
Canada logos and corporate identity), but will be properly cited. 
4. Participants will complete again the BSAS and the questions on booster seat guidelines. 
5. Participants in the intervention group will be asked one or two multiple choice questions to 
ensure they did not misunderstood the information in an unintended way. These questions 
will be designed based on the information on adverse effects collected during the focus 
groups and the trial’s pilot. If a parent answers incorrectly, the system will clarify the 
information immediately after. 
6. Participants in the control group will be given the option to view the enhanced booster seat 
material, in order to give them the opportunity to benefit from the intervention. 
 
Analysis. The online version of the Booster Seat Attitudes Scale will be factor-validated and 
Cronbach’s alpha of each BSAS subscale will be calculated to determine reliability. The effect of 
the intervention on the Benefit, Intention, and Self-Efficacy subscales of the BSAS will be 
examined through linear mixed effects models with random effects by province (to account for 
between-province differences in legislation and booster seat education programs). Multiple 
imputation will be used to address missing data. Intention-to-treat analysis will be conducted, by 
doing two separate analyses: one with the entire sample of participants and one with only 
participants who complete the trial. In addition, mediation analysis will be conducted to 
determine if perceived safety benefit mediated the effect of the intervention on intent to use 
booster seats. Dropout curves will be used to examine in which part of the trial participants in 
each condition were more or less likely to drop out. Student’s t, Wilcoxon Sign and Rank, or 
Mann-Whitman’s U tests will be used to compare, across groups, subjective estimates of the 
impact of the intervention on other parents, time spent reading the material, number of clicks on 
links to additional booster seat information, and pre- versus post-intervention difference in 
subjective estimates of the risk reduction afforded by booster seats and by seatbelts. 
 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
UPDATE 27 OF JUNE 2019: 
Increase in perceived safety benefit of booster seats (primary outcome) and increase in 
intention to use booster seat (a secondary outcome) were evaluated by, first calculating the 
difference between the post-intervention score and the pre-intervention score for each 
participant. This difference was then compared with t tests (two-tailed). Parents’ judgments of 
the impact of the intervention on their peers (a secondary outcome), which was assessed post-
intervention only, was compared across study arms with the t tests (two-tailed). The same 
statistical analysis was used to evaluate the other secondary outcomes (parents’ recall of 
booster seat information, Interest in booster seat information). 
Intent to treat analysis was conducted by examining the sensitivity of the study to extreme 
values. Two additional statistical analyses were conducted for each outcome measure; one 
where missing values resulting from participant dropouts were imputed the highest possible 
score, and one where missing values were imputed the lowest possible scores. 
 
Ethical considerations 
There are three ethical considerations in the present research project: (1) informed consent, 
(2) risk to participants, (3) withholding a potentially beneficial treatment to participants. Informed 
consent will be obtained in both phases of the project. Consent to participate in the focus groups 
and pilot test will be signed on paper, and consent to participate in the online trial will be digital. 
Focus groups in the development phase do not entail any known physical risk. Furthermore, 
psychological risks to participants in the focus groups meet the TCPS2 definition of minimal 
risk.48 The topics, information, and content to be discussed or provided to parents is in the 
public domain (i.e., how booster seats work, and current booster seat legislation and 
guidelines). As a result, the risk of psychological reactions (unpleasant emotions and stress) to 
the information or survey questions is not greater than the risk they would experience when 
looking at online information on booster seats. Moreover, if parents are not aware that such 
information is available, it is actually beneficial for them to know it exists. Social risks to 
participants in the focus groups (embarrassment, stigma) also meet the definition of minimal 
risk. It is conceivable that some participants may reveal that they do not restrain their children in 
a booster seat, which is mandatory in British Columbia. However, non-use of booster seats is 
easily observable by any person standing near the vehicle (e.g., neighbor, passerby). Thus, 
participation in the focus groups poses no greater risk of embarrassment or stigma than that 
encountered by the same parents in their own neighborhood or a parking lot. 
The trial phase also poses minimal risk to participants. There is no known physical risk. In 
addition, psychological risks are not greater than the risk parents experience when looking at 
information on booster seats, because the information provided to the control and intervention 
groups is available to any parent interested in booster seat information. Social risks are less of a 
problem, given that the survey will be conducted entirely online. It is conceivable that a small 
number of participants may incorrectly interpret the information as “seatbelts are unsafe.” 
However, any potential of misapprehension of the information provided to the control or the 
intervention group will be reduced during in the development phase and during pilot testing. 
Finally, the trial design implies that half of the participants will not be exposed to a potentially 
beneficial intervention. To remedy this problem, participants in the control group will be exposed 
to the intervention after they complete the trial. The same safeguards to prevent 
misinterpretation will be applied to them. 
 
Knowledge Translation potential 
Findings from the present study can be quickly implemented in many settings, considering 
how ubiquitous the internet is and how fast the information online can be updated. Transport 
Canada, Parachute, BCAA, and Saskatchewan General Insurance, ICBC, and any other 
stakeholder with online presence can enhance their booster seat information page, by adding 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
the proposed intervention. Furthermore, pediatricians, family doctors, and emergency 
physicians, who often give safety advice to parents,49 can also use this information by providing 
parents with a link to any aforementioned websites. In terms of knowledge translation, the most 
useful feature of the intervention is that information about how seatbelts and booster seats 
prevent injuries remains true regardless of legislation differences between jurisdictions. Thus, 
the potential impact of this research extends across provinces, countries, and continents. 
An important advantage of the narrow scope I adopted here is that I am developing and 
testing a psychological principle that can be applied in different contexts: if the present study 
successfully and safely demonstrates that explaining the concept of redirecting crash forces 
increases perceived benefit and intention to use booster seats, then the same principle can be 
tested in face-to-face child seat clinics or social marketing campaigns. 
 
Budget 
 
Source 
Justification 
Subtotal 
PhD Student stipend 
UBC, Public Scholars 
Initiative 
$7,000/year 
$7,000 
Compensation focus group and 
RCT piloting 
Evidence to 
Innovation Seed 
Grant 
(16 focus groups + 
10 RCT pilot) × $50 
each1 
$1,300 
Participant recruitment for RCT 
Evidence to 
Innovation Seed 
Grant 
$9.40 × 606 
completed surveys 
$5,700 
Total 
$14,000 
 
 
 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
Timeline 
Activity 
Dec 
Jan 
Feb 
Mar 
Apr 
May 
Jun 
Jul 
Aug 
Development of education material 
 
 
 
 
 
 
 
 
 
Focus group testing and adjustments 
 
 
 
 
 
 
 
 
 
Ethics certificate amendment 
 
 
 
 
 
 
 
 
 
Data collection 
 
 
 
 
 
 
 
 
 
Data analysis 
 
 
 
 
 
 
 
 
 
Report writing 
 
 
 
 
 
 
 
 
 
 
References 
1.  
Klinich, K.D., Manary, M.A., Weber K. Crash Protection for Child Passengers : Rationale 
for Best Practice. UMTRI Res Rev. 2012;43(1):35. 
2.  
Arbogast KB, Kent RW, Menon RA, Ghati Y, Durbin DR, Rouhana SW. Mechanisms of 
abdominal organ injury in seat belt-restrained children. J Trauma. 2007;62(6):1473-1480. 
doi:10.1097/01.ta.0000231965.20704.16 00005373-200706000-00028 [pii]. 
3.  
Durbin DR, Arbogast KB, Moll EK. Seat belt syndrome in children: a case report and 
review of the literature. Pediatr Emerg Care. 2001;17(6):474-477. 
http://www.ncbi.nlm.nih.gov/pubmed/11753199. 
4.  
Santschi M, Lemoine C, Cyr C. The spectrum of seat belt syndrome among Canadian 
children: Results of a two-year population surveillance study. Paediatr Child Health. 
2008;13(4):279-283. 
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2529446&tool=pmcentrez&ren
dertype=abstract. Accessed April 29, 2016. 
5.  
Snowdon AW, Hussein A, Ahmed E. Canadian National Survey on Child Restraint Use 
2010. AUTO21; 2011. 
6.  
Gray CE, Larouche R, Barnes JD, et al. Are we driving our kids to unhealthy habits? 
Results of the active healthy kids Canada 2013 report card on physical activity for 
children and youth. Int J Environ Res Public Health. 2014;11(6):6009-6020. 
doi:10.3390/ijerph110606009. 
7.  
Skjerven-Martinsen M, Naess PA, Hansen TB, Rognum TO, Lereim I, Stray-Pedersen A. 
In-depth evaluation of real-world car collisions: fatal and severe injuries in children are 
predominantly caused by restraint errors and unstrapped cargo. Traffic Inj Prev. 
2011;12(5):491-499. doi:10.1080/15389588.2011.596868. 
8.  
World Health Organization. Global Plan for the Decated of Action for Road Safety 2011-
2020.; 2011. 
9.  
World Health Organization. National plans for the Decade of Action for Road Safety 
2011-2020. http://www.who.int/roadsafety/decade_of_action/plan/national/en/. Published 
2016. Accessed December 9, 2016. 
10.  
Transport Canada. Road Safety in Canada. 
http://www.tc.gc.ca/eng/motorvehiclesafety/tp-tp15145-1201.htm#intro4. Published 2016. 
Accessed December 9, 2016. 
11.  
Silcoff S. New $450 car seat promises to keep your child safer in an accident. The Globe 
and Mail. October 2012. 
12.  
Child Passenger Safety Association of Canada. Provincial & Territorial Legislation 
Summary Province/Territory -revised May-2016. 2016. http://www.cpsac.org/caregiver-
resources/. 
13.  
Safe Kids Canada. Child Safety Good Practice Guide. Toronto, ON; 2011. 
14.  
Ehiri JE, Ejere HOD, Hazen AE, Emusu D, King WD, Osberg SJ. Interventions to 
Increase Children’s Booster Seat Use: A Review. Am J Prev Med. 2006;31(2):185-192. 
http://www.sciencedirect.com/science/article/pii/S0749379706001474. 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
15.  
Canada T. Car Seats, Seat Belts and Your Child. 
http://www.tc.gc.ca/eng/roadsafety/safedrivers-childsafety-car-index-873.htm. Published 
2012. 
16.  
Snowdon A, Rothman L, Slater M, et al. A comparison of booster seat use in Canadian 
provinces with and without legislation. Inj Prev. 2009;15(4):230-233. 
doi:10.1136/ip.2008.020537. 
17.  
Simniceanu A, Richmond SA, Snowdon A, Hussein A, Boase P, Howard A. Child 
Restraint Use in Canadian Provinces With and Without Legislation in 2010. Traffic Inj 
Prev (. 2014;15(7):734-739. 
18.  
Yanchar NL, Young JB, Langille DB. Knowledge and practice of childhood motor vehicle 
restraint use in Nova Scotia: Phase II. Accid Anal Prev. 2015;74(2015):150-156. 
19.  
Cunningham CE, Bruce BS, Snowdon AW, et al. Modeling improvements in booster seat 
use: a discrete choice conjoint experiment. Accid Anal Prev. 2011;43(6):1999-2009. 
doi:10.1016/j.aap.2011.05.018. 
20.  
Bruce BS, Snowdon AW, Cunningham C, et al. Predicting parents’ use of booster seats. 
Inj Prev. 2011;17(5):313-318. doi:10.1136/ip.2010.029181. 
21.  
Emery KD, Hawkes AP, Cassabaum V, Rapstine T. Junglemobile: a mobile injury-
prevention program for young children. J Trauma Nurs. 2016;17(1):19-27. 
doi:10.1097/JTN.0b013e3181d91605. 
22.  
Howard A, Beben N, Rothman L, Fiissel D, MacArthur C. Evaluation of Safe Kids Week 
2004: age 4 to 9? It’s booster seat time! Inj Prev. 2006;12(5):316-319. 
doi:10.1136/ip.2006.012138. 
23.  
Apsler R, Formica SW, Rosenthal AF, Robinson K. Increases in booster seat use among 
children of low income families and variation with age. Inj Prev. 2003;9(4):322-325. 
doi:10.1136/ip.9.4.322. 
24.  
Keay L, Hunter K, Brown J, et al. Evaluation of an Education, Restraint Distribution, and 
Fitting Program to Promote Correct Use of Age-Appropriate Child Restraints for Children 
Aged 3 to 5 Years: A Cluster Randomized Trial. Am J Public Health. 2012;102(12):e96-
e102. doi:10.2105/AJPH.2012.301030. 
25.  
Aitken ME, Miller BK, Anderson BL, et al. Promoting Use of Booster Seats in Rural Areas 
Through Community Sports Programs. J Rural Heal. 2013;29(s1):s70-s78. 
doi:10.1111/jrh.12000. 
26.  
Johnston BD. A preschool program for safety and injury prevention delivered by home 
visitors. Inj Prev. 2000;6(4):305-309. doi:10.1136/ip.6.4.305. 
27.  
Quinlan KP, Holden J, Kresnow M-J. Providing car seat checks with well-child visits at an 
urban health center: a pilot study. Inj Prev. 2007;13(5):352-354. 
doi:10.1136/ip.2006.015099. 
28.  
Bowman JA, Sanson-Fisher RW, Webb GR. Interventions in Preschools to Increase the 
Use of Safety Restraints by Preschool Children. Pediatrics. 1987;79(1):103-109. 
www.ncbi.nlm.nih.gov. 
29.  
Ebel BE, Koepsell TD, Bennett EE, Rivara FP. Use of Child Booster Seats in Motor 
Vehicles Following a Community Campaign. JAMA. 2003;289(7):879-884. 
doi:10.1001/jama.289.7.879. 
30.  
O’Neal J. Methods to increase booster seat use in 4 to 6 year old children. In: The 49th 
AAAM Annual Conference, 2005. ; 2005. 
31.  
Stevens SL. Effects of intervention on booster seat purchase: a field study. 2000. 
32.  
Gittelman MA, Pomerantz WJ, Laurence S. An emergency department intervention to 
increase booster seat use for lower socioeconomic families. Acad Emerg Med. 
2006;13(4):396-400. doi:10.1197/j.aem.2005.11.002. 
33.  
Gittelman M a, Pomerantz WJ, Ho M, Hornung R, McClanahan N. Is an emergency 
department encounter for a motor vehicle collision truly a teachable moment? J Trauma 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov 
 
 
Acute Care Surg. 2012;73(4 Suppl 3):S258-61. doi:10.1097/TA.0b013e31826b0161. 
34.  
Snowdon AW, Hussein A, Purc-Stevenson R, Follo G, Ahmed E. A longitudinal study of 
the effectiveness of a multi-media intervention on parents’ knowledge and use of vehicle 
safety systems for children. Accid Anal &amp; Prev. 2009;41(3):498-505. doi:S0001-
4575(09)00022-0 [pii] 10.1016/j.aap.2009.01.013. 
35.  
Canada PHA of. Table 1: Leading causes of death, Canada, 2005, males and females 
combined: counts (crude death rate per 100,000). lcd-pcd-t1-eng, ed. pdf. 2008. 
36.  
Public Health Agency of Canada. Injury in Review: Spotlight on Road and Transport 
Safety. Ottawa, ON; 2012. 
http://www.parachutecanada.org/downloads/research/reports/InjuryInReview2012_EN.pd
f. 
37.  
Arbogast KB, Jermakian JS, Kallan MJ, Durbin DR. Effectiveness of belt positioning 
booster seats: an updated assessment. Pediatrics. 2009;124(5):1281-1286. 
doi:10.1542/peds.2009-0908. 
38.  
Groff P. The Injury Prevention Spectrum and the 3 E’s. In: Pike I, Richmond S, Rothman 
L, Macpherson A, eds. Canadian Injury Prevention Resource. 1.2. Toronto, ON: 
Parachute; 2015:52-55. 
39.  
Keay L, Hunter K, Brown J, et al. Child restraint use in low socio-economic areas of urban 
Sydney during transition to new legislation. Accid Anal &amp; Prev. 2012;50:984-991. 
http://www.sciencedirect.com/science/article/pii/S0001457512002898. 
40.  
Reyna VF. A theory of medical decision making and health: fuzzy trace theory. Med 
Decis Mak. 2008;28(6):850-865. doi:10.1177/0272989X08327066. 
41.  
Brixey SN, Guse CE. Knowledge and behaviors of physicians and caregivers about 
appropriate child passenger restraint use. J Community Health. 2009;34(6):547-552. 
doi:10.1007/s10900-009-9176-2. 
42.  
Snowdon AW, Polgar J, Patrick L, Stamler L. Parents’ Knowledge about and Use of Child 
Safety Systems. Can J Nurs Res. 2006;38(2):98-114. 
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation
&list_uids=16871853. 
43.  
Margolis LH. Use and Misuse of Automobile Child Restraint Devices. Aidc. 1992;146:361-
366. doi:10.1001/archpedi.1992.02160150101032. 
44.  
Transport Canada. Stage 3: Booster Seats - Transport Canada. 
https://www.tc.gc.ca/eng/motorvehiclesafety/safedrivers-childsafety-stage3-booster-
seats-1086.htm. Published 2016. Accessed October 1, 2016. 
45.  
Snowdon AW, Hussein AA, Ahmed SE. Children at risk: predictors of car safety seat 
misuse in Ontario. Accid Anal Prev. 2008;40(4):1418-1423. doi:S0001-4575(08)00045-6 
[pii]10.1016/j.aap.2008.03.004. 
46.  
Golonka RP, Dobbs BM, Rowe BH, Voaklander D. Prevalence and predictors of booster 
seat use in Alberta, Canada. Can J Public Heal. 2016;107(2):155. 
doi:10.17269/cjph.107.5254. 
47.  
Macpherson AK, Brussoni M, Fuselli P, Middaugh-Bonney T, Piedt S, Pike I. An 
evaluation of evidence-based paediatric injury prevention policies across Canada. BMC 
Public Health. 2015;15:707. doi:10.1186/s12889-015-1986-9. 
48.  
Canadian Institutes of Health Research, Natural Sciences and Engineering Research 
Council of Canada, Social Sciences and Humanities Research Council of Canada. Tri-
Council Policy Statement.; 2010. 
49.  
Zonfrillo MR, Sauber-Schatz EK, Hoffman BD, Durbin DR. Pediatricians’ self-reported 
knowledge, attitudes, and practices about child passenger safety. J Pediatr. 
2014;165(5):1040-5-2. doi:10.1016/j.jpeds.2014.07.041. 
50.  
Elster J. Explaining Social Behaviour: More Nuts and Bolts for The Social Sciences.; 
2007. Elster 2007 - Explaining social behaviour.pdf TS  - WorldCat. 

Communicating the safety benefit of booster seats 
Takuro Ishikawa 
Version 4.0 – 27 June 2019 – Registered in ClinicalTrials.gov