Correlation between tea use and personality
Correlation between tea use and personality
Jaap Bierman, Berber de Vries, Alwin Zwets
Media Technology programme, Leiden University
personalities of drinkers and non-drinkers,
between tea and coffee users nor is there a
correlation between tea use and the level of
dubiousness. Agreeableness was measured using the Big Five Inventory and
drinking of tea and coffee. This research
clicks while making the questionnaire.
aims to compare personality traits of people that drink many cups of tea to that
: Tea; Coffee; Personality;
of those who drink few or none at all. The
total amount of caffeine intake is not taken into account.
media, is that heavy tea users will be more
agreeable and dubitable. The personality
countries, drinking tea is a tradition that
characteristics will be compared to those of
Netherlands, tea is the second most drunk
beverage on a yearly basis (CBS 1997). With its 100 liters of tea per person per
year, it is second to coffee, which has a
On a daily basis, most people prefer one
backgrounds (mode = science education, n
claims are made that people who drink tea
42). The questionnaire consists of the big
five personality test, questions on beverage use and cover questions to hide the
In the past, several researches have been
purpose of the test and to prevent socially
done trying to find a correlation between
drinking habits and personality. In these
tests, tea and coffee were used in the same
two or more cups of the certain beverage a
category, that of caffeinated beverages.
Richardson et al. (1995) compared caffeine
To measure the personality traits of the
that the first were more extroverted and
Inventory (BFI) by Oliver P. John (1991).
had higher addiction scores. The addiction
factor is also studies by Brice and Smith
between personality and the use of caffeine
drinks, alcoholic drinks and smoking. They
dubiousness the number of clicks made in
A Shapiro-Wilk test as well as a Skewness/
the questionnaire was recorded where the
Kurtosis test was done to confirm that the
Neither the first test (z = 0,24) nor the latter (chi2 = 0,10) did reject the
Three participants were removed from the
distributed. Finally, a variance-comparison
tests showed that there is no significance
clicks and one in the agreeableness factor,
difference (c = 0,74) in the variances of the
had to be discarded because the statistical
two variables (1,05 and 0,99 respectively).
test used, a t-test, is not robust to outliers.
significant difference ( = 0,18) between
the two groups. (μ1 = 3,35, μ2 = 3,25).
agreeableness of our often-tea drinking group (μ1) is higher than those who do not
often drink tea (μ2).
The same testing is done for the amount of
clicks, which could indicate more dubitability for tea drinkers.
needed be normalised in order to check if both data groups have a normal
distribution and their variance is equally distributed.
Graph 2: Histogram of normalised clicks.
For normality testing, first a histogram
The analysis of the amount of click data
revealed a huge positive skew, as can be
seen in Graph 2
. Also, both the Shapiro-
Wilk test and the Skewness/Curtosis test
rejected the normality assumption, which subsequently make a t-test invalid.
A variance-ratio test would be meaningless since the data is not normally distributed. This also holds for the t-test, which had an
outcome of = 0,08, with μ1 = 59,2 and μ2
= 57,8; thus the difference in clicks is non-
The results of this study reject the
hypothesis that heavy tea users are more
consumers. Further research is required to
determine whether there is no correlation between personality and tea at all, or that
dubiousness. Also the correlation between
coffee and personality can be investigated.
could be done concerning the ‘heavy use’ mark. While in this study this is stated as
In following studies, a larger number of
equal distribution in all social groups. This
is to be sure that the investigated group is
Brice, C. F., Smith, A. P. (2002) Factors associated with caffeine consumption. International Journal of Food Sciences and Nutrition Vol. 53: p. 55-64
Centraal Bureau voor de Statistiek (1997), Nederlanders drinken minder koffie. http://bit.ly/a70FzK Last requested on Nov. 20th 2010
Digman, J.M. (1990), Personality Structure: Emergence of the Five-Factor Model. Annual Review of Psychology Vol. 41: p. 417-440
Hewlett, P., Smith, A. (2006) Correlates of daily caffeine consumption. Appetite Vol. 46: p. 97-99
John, O.P. (1991), The Big Five Personality Inventory. Eugene, University of Oregon
Richardson, N. J., Rogers, Peter J., Elliman, N. A., O’Dell, R. J. (1995) Mood and performance effects of caffeine in relation to acute and chronic caffeine deprivation. Pharmacology Biochemistry and Behavior Vol. 52: p. 313-320
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