In January 2020, PenCTU held a mock Randomised Controlled Trial, the Chocolate Trial, as part of the University of Plymouth’s 2020 Research Festival. 

University staff, students and members of the public were invited to participate, with the aim of engaging the public and improving knowledge and understanding of clinical trials and the role they play in the advancement of medical and healthcare treatments.

The Chocolate Trial investigated whether flavoured chocolate improved mood more than plain chocolate.

What did we do?

  • We ‘recruited’ participants to the trial and obtained their informed consent.
  • We measured participants’ mood before and after eating a piece of chocolate using a 0-10 sliding scale.
  • We ‘randomised’ participants to either the control group (‘plain’ chocolate) or the intervention (‘flavoured’ chocolate).
  • To make the study a fair comparison, participants did not know whether they were given plain or flavoured chocolate (this is known as ‘blinding’). We asked participants to guess which chocolate they had eaten.
  • After completing The Chocolate Trial, we asked whether participants understanding of clinical trials had changed.
  • Data were captured using PenCTU’s instance of REDCap Cloud (a clinical trial electronic data capture system), and exported directly in to the statistical software package "R" in real time, for the purposes of live reporting, visualisation and analysis.

Who took part?

  • 51 participants took part in the trial over the two one-hour sessions (25 allocated to plain chocolate and 26 allocated to flavoured chocolate).
  • Just over half of the participants were University staff.
  • Nearly two thirds were female.
  • There was a wide range of age amongst the participants.

Does flavoured chocolate improve mood more than plain chocolate?

  • Participant’s mean mood before chocolate (baseline) was 6.5 and after chocolate (follow-up) was 7.4 points. Figure 1 summarises participants’ change in mood between baseline and follow-up.
  • The mean change in mood after eating chocolate was 1.2 points for the plain chocolate and 0.6 points for the flavoured chocolate.
  • Plain chocolate improved participant’s mood by around 0.6 points more than the flavoured chocolate.
  • The 95% confidence interval for the difference in change in mood was -0.1 to 1.2 points.
  • This shows that whilst there is some suggestion that plain chocolate is better than flavoured chocolate at improving mood, the difference is not statistically significant.

Could participants guess correctly their allocated chocolate?

Whilst the two chocolates looked very similar, most participants were able to correctly identify which chocolate they had eaten:

  • 81% of participants who ate the flavoured chocolate guessed correctly.
  • 96% of participants who ate the plain chocolate guessed correctly.

One participant who ate the plain (control) chocolate guessed incorrectly; this demonstrates the ‘placebo effect’, where a participant’s expectation of the treatment (chocolate) may affect their perceived experience.

Did the Chocolate Trial increase understanding of clinical trials?

  • 86% of participants provided feedback on whether their understanding of clinical trials had increased.
  • 73% of participants providing feedback said that their understanding of clinical trials had increased; almost half (43%) reported that their understanding increased a lot (Figure 2).

What did participants think about the event?

Participant’s feedback was overwhelmingly positive (Figure 3)

  • “A great overview of a clinical trial.”
  • “Great friendly staff. Great to see a trial in action.”
  • “Great way to improve people’s understanding at what’s involved in clinical trials.”
  • “Good fun practical way to introduce people to the concept of clinical trials.”

The Chocolate Trial – results summary