36.2 Example 1: Reading research
A study (Fritts et al. 2018) explored the impact of adding herbs and spices to the consumption of vegetables by adolescent school children. Part of the Abstract states (slightly edited for brevity):
Purpose: We evaluated whether new vegetable recipes using herbs and spices would increase preference for vegetables served to adolescents at this school.
Methods: To evaluate recipe acceptance, we assessed liking (100 mm visual analog scales) among students (\(n =\) 96–110; aged 14–18 years) for 8 plain (oil and salt) and 8 seasoned vegetables. Liking ratings between plain and seasoned vegetables were compared with paired \(t\)-tests…
Results: Students reported higher liking for several seasoned recipes compared to plain: broccoli (\(P = 0.02\)), vegetable dip (\(P < 0.0001\)), black beans and corn (\(P < 0.001\)) and cauliflower (\(P < 0.0001\)).
Conclusions: Common herbs and spices improved liking for several school lunch vegetables compared to plain varieties among rural high school students…
— Fritts et al. (2018), p. 125
Later we read this (again, slightly edited):
This is a cross-sectional study assessing preference for plain and seasoned vegetables in a population of middle/high school students (aged 14–18 years) attending a rural Pennsylvania public school.
— Fritts et al. (2018), p. 126
Even using this (small amount) of information, much can be learnt about the study. For example:
Ask the question: The POCI elements are:
- Population: ‘middle/high school students (aged 14–18 years) attending a rural Pennsylvania public school’
- Outcome: The mean difference in taste ratings between plain and seasoned vegetables. The taste ratings are given using a ‘100 mm visual analog scale.’
- Comparison: There is no comparison: Every member of the population is treated the same way. A comparison exists if different subsets of the population are treated differently (for example, one group of students is given plain vegetables, and a different group is given seasoned vegetables).
- Intervention: No; there is no comparison, so there is no comparison to be allocated.
Design the study: Since this RQ is descriptive, the study is * descriptive. The participants were probably not blinded*, since the presence of seasoning was probably obvious.
Collect the data: No details are given about the data collection.
Describe and summarise the data: The Abstract gives no summary data (since eight vegetables were studied, this would have consumed too much space I guess).
Analyse the data: The data were analysed using paired \(t\)-tests, one for each different vegetable used. (Each subject gave two ratings for each vegetable: one for plain vegetables and one for seasoned vegetables),
Report the results: Evidence exists of a men difference (that students preferred the seasoned vegetables) in many cases, but not all (the Abstract states that eight vegetables were used, with statistically significant differences for five).
From this information, the RQ is something like:
For middle/high school students (aged 14–18 years) attending a rural Pennsylvania public school, is there a mean difference in taste ratings (measured on a ‘100 mm visual analog scale’) between plain and seasoned vegetables?
For more details, the whole paper could be read.