Optimizing Weblinks Used in Digital Vaccination Invitations to Raise Trust and Booking Intention: Online Experiment 3
Phase: NA
Conditions: Vaccination
Sponsor: University of Essex

Document related to the study: “Optimizing Weblinks Used in Digital 
Vaccination Invitations to Raise Trust and Booking Intention: Online 
Experiment 3” 
 
The document was registered on AsPredicted on the 02/01/2022 
 
 
The document includes hypotheses, design, dependent variables and analytical plan for the 
study “Optimizing Weblinks Used in Digital Vaccination Invitations to Raise Trust and 
Booking Intention: Online Experiment 3” 

Version of AsPredicted Questions: 2.00
PDF generated: 2026/02/09 01:43 (PT)
Available at https://aspredicted.org/92nt-brgg.pdf
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Foster trustworthy digital communication about vaccines with better links S3 (#86763)
Author(s)
This pre-registration is currently anonymous to enable blind peer-review.
It has one author.
Pre-registered on:
2022/02/01 08:41 (PT)
1) Have any data been collected for this study already?
No, no data have been collected for this study yet.
2) What's the main question being asked or hypothesis being tested in this study?
Participants will read one of three emails of invitation to get a booster vaccine.
One email will include the accurx web link that was used by the NHS and the other one will include an improved version of it,
a third one will include only a hyperlink.
The UK and US samples will be shown slightly diﬀerent emails.
.
Hypotheses
1. The email that includes the accurx web link will be perceived as less trustworthy, than the other emails
2. Participants will be more likely to agree to book a vaccine appointment based on the email that includes the improved link or the hyperlink
3. Participants will ﬁnd the improved link and the hyperlink more ﬂuent than the accurx web link.
4. Participants will be more likely to correctly identify the organisation hosting the link based on the improved link and the hyperlink than based on
the accurx web link.
5. Identifying the organisation hosting the link will have more beneﬁcial eﬀect in the UK than in the US.
3) Describe the key dependent variable(s) specifying how they will be measured.
Participants will rate each text message in terms of how trustworthy it seems on a 5 point Likert scale (1: Very suspicious to 5: very trustworthy),
how ﬂuent
is the link on a 5 point Likert scale (1: very diﬃcult – 5: very easy) and how likely they would be to book an appointment on a 5 point Likert scale (1:
very
unlikely to 5: very likely). To identify the host organisation of the website, participants will select one answer from a list of four possible answers (the
NHS,
pharma-us, accurx or unclear/I don't know).
4) How many and which conditions will participants be assigned to?
Participants will be allocated to one of three email conditions.
5) Specify exactly which analyses you will conduct to examine the main question/hypothesis.
We will test hypotheses 1-3 and 5 with a within-subject analysis of variance with the web link manipulation (3 conditions) as between
subject factors and the diﬀerent variable about the email perception as dependent variables.We will conduct the analysis separately for the UK and
US data.
We will test hypothesis 4 with a chi square.
We will also test the robustness of the eﬀect by including participants' sociodemographic characteristics (e.g., gender, age, education).
6) Describe exactly how outliers will be deﬁned and handled, and your precise rule(s) for excluding observations.
We will ﬁlter participants out if we judge they completed the study too fast or failed the attention check.
7) How many observations will be collected or what will determine sample size? No need to justify decision, but be precise about
exactly how the number will be determined.
We aim to gather data from 4000 participants (2000 from the US and 2000 from the UK).
8) Anything else you would like to pre-register? (e.g., secondary analyses, variables collected for exploratory purposes, unusual
analyses planned?)
The study is part of a wider web survey that includes questions about the trustworthiness of text messages and vaccination rates.