Effects of a Single Dose of Wild Blueberries on Mood and Executive Function in Healthy Emerging Adults: a Single-Blind, Randomized Controlled Trial
Phase: NA
Conditions: Mood, Affect, Executive Function
Sponsor: University of Reading

 
 
 
 
Study Protocol and Statistical Analysis Plan 
Study title: Effects of a Single Dose of Wild Blueberries on Mood and Executive Function in 
Healthy Emerging Adults 
Date: 28 January 2023 
 
 
 
 
 
 
 
 
 
 
 

1. Sample Size Calculation 
An independent samples t-test power calculation in G*Power using positive affect (PANAS-X) 
as an outcome variable with an effect size d = 0.5 based on a previous study and α = 0.05 (one 
tailed) indicates that 78 participants (39 for each group) will be required to achieve power of 
0.70 (probability of correctly rejecting the null hypothesis). 
2. Recruitment  
Participants will be recruited primarily through the SONA Research Participant System at the 
School of Psychology and Clinical Language Sciences and through email distribution  
3. Randomization and Blinding Process  
A researcher not involved in recruitment or data collection will use blocked randomization with 
random permuted blocks of two individuals to form the allocation list for the two comparison 
groups. The allocation sequence will be generated using the online randomization tool Sealed 
Envelope (v1.19.1) and will be concealed to the researchers enrolling participants. The 
intervention drinks will be administered in opaque shaker bottles. 
5. Statistical Analysis Plan   
The outcomes will be analyzed using ANCOVAs adjusted for baseline values and habitual fruit 
and vegetable intake as long as the assumptions for conducting the analysis are met.