| Convert Raw Scores
to Cumulative Percentages
Step 3: Compute the Cumulative Frequency.
The
next step is to compute the cumulative frequency (cf). In order
to do this, look at the numbers that were entered into the
frequency (f) column and add them up. 2+7+3+1+2=15. This will
give you the number of scores that are at or below the X value
of 99. Place the number 15 in the column labeled cf. (Note:
The highest score in the X column will equal cf=∑f. In this
case, cf=∑f corresponds to X=99. Because all of the scores
in the distribution are at or below X=99; X=99 also corresponds
to the 100th percentile.)
 To determine the cumulative frequency (cf) of X=80, add together
the numbers in the f column beneath 7 and include 7. For example,
add 7+3+1+2=13. Record 13 in the cf column across from X=80.
 Next find the cumulative frequency (cf) for X=60. Now you
will add together 3+1+2=6. Record 6 in the chart below cf
across
from X=60.
 Next, find the frequency of X=59. In order to do this, add
1+2=3 and enter 3 in the column under cf across from X=59.
 Next, find the frequency of X=25. X=25 occurs 2 times. Therefore,
the frequency of X=25 is 2. Record 2 in the column under cf
across from X=25.
Continue to Step 4: Compute the
Cumulative Percentage. Copyright 2005 by the
Academic Center and the University of Houston-Victoria.
Created 2004 by Maranda Koenig. Content Reviewed by Hari
Damodaran. Edited by Sandra Heinold. |
