Transcript Interpretation and Analysis of Data

Interpretation and Analysis of Grouped
Data
Sometimes we have a frequency table like this:
Absences
(d days)
Frequency
0d5
4
5  d  10
6
10  d  15
8
15  d  20
5
20  d  25
4
25  d  30
3
With this type of data
we do not know the
value of the number of
absences so we
estimate it using the
midpoint
We use the mid-point
as we must assume
that there is an even
distribution of data in
the group.
Absences (d days) Frequency
Mid point
0d5
4
2.5
5  d  10
6
7.5
10  d  15
8
12.5
15  d  20
5
17.5
20  d  25
4
22.5
25  d  30
3
27.5
The mean number of days absence is given by:
415  30 = 13.8 days
Absences Frequenc Mid point
y
(d days)
2.5
0d5
4
Mid Absences
 frequency
2.5 x 4 = 10
5  d  10
6
7.5
7.5 x 6 = 45
10  d  15
8
12.5
12.5 x 8 = 100
15  d  20
5
17.5
17.5 x 5 = 87.5
20  d  25
4
22.5
22.5 x 4 = 90
25  d  30
3
27.5
27.5 x 3 = 82.5
Totals
30
415