RESEARCH METHOD COHEN ok

MEASURES OF DIFFERENCE BETWEEN GROUPS AND MEANS 545
picture of the situation than the teachers, and that
the teachers – the ones who have to work with
the students on a close daily basis – are more in
touch with the students and know that there are
problems, a matter to which the senior managers
may be turning a blind eye.
In reporting the t-test here the following form
of words can be used:
The mean score of the leaders/SMT on the variable
‘How well learners are cared for, guided and
supported’ (M = 8.37, SD = 2.085 is statistically
significantly higher (t = 2.02, df = 811.922, twotailed
(ρ = 0.044) than those of teachers on the
same variable (M = 8.07, SD = 2.462).
Let us take a second example. Here the
leaders/SMT and teachers are voting on ‘the
attention given to teaching and learning in the
school’, again awarding a mark out of 10, i.e. ratio
data. The mean for the leaders/SMT is 5.53 and for
the teachers it is 5.46. Are these means statistically
significantly different (Boxes 24.39 and 24.40)
If we examine the Levene test (Sig.) we find that
equal variances are assumed (ρ = 0.728), i.e. we
remain on the top row of the data output. Running
along to the column headed ‘Sig. (2-tailed)’ we
find that ρ = 0.610, i.e. there is no statistically
significant difference between the means of the
two groups, therefore the null hypothesis (there
is no statistically significant difference between
the means of the two groups) is supported. This
should not dismay the researcher; finding or not
finding a statistically significant difference is of
equal value in research – a win-win situation.
Chapter 24
Box 24.39
At-testforleadersandteachers
Group statistics
The attention given to
teaching and learning at
the school
Who are you N Mean SD SE mean
Leaders/SMT member
Teachers
347
653
5.53
5.46
2.114
2.145
0.113
0.084
Box 24.40
The Levene test for equality of variances between leaders and teachers
Independent samples test
Levene’s test
for equality
of variances
t-test for equality of means
The attention
given to
teaching and
learning at
the school
Equal variances
assumed
95 % confidence
interval of the
difference
Sig. Mean SE
F Sig. t df (2-tailed) difference difference Lower Upper
0.121 0.728 0.510 998 0.610 0.07 0.142 −0.206 0.351
Equal variances 0.513 714.630 0.608 0.07 0.141 −0.205 0.350
not assumed