Casimiro, Haizelyn N. Endaya, Dominique Francesca E. Grumo, Rona Rose A.
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Transcript of Casimiro, Haizelyn N. Endaya, Dominique Francesca E. Grumo, Rona Rose A.
Casimiro, Haizelyn N.
Endaya, Dominique Francesca E.
Grumo, Rona Rose A.
POINT BISERIAL COEFICIENT OF
CORRELATION (rpb)
The point biserial correlation is a measure of association between a continuous variable and a binary variable (Simon, 2005-2008).
The formula, according to Vizcarra, 2003:
1rpb 2121
nn
nn
s
xx
x
Where: = Point biserial coefficient
= Mean of the interval or ratio scale variable of one group (x)
= Mean of the other group (y)
= Number of population of one group
= Number of population in the other group
= Total number of population ()
= Standard Deviation of the two groups
rpb
1x
2x
1n
2n
n
SD
EXAMPLE:The researcher would like to determine if the
scores of 16 students of the same school on a 20-point math test is associated with their gender. Boys
(X1)Girls (X2)
14 15
12 10
19 9
11 7
9 8
7 19
6 16
18 11
Total = 95
Total = 96
STEPS:1. Compute the mean of X1 and X2.
= 11.87 = 122. Compute the standard deviation of X and Y
using the formula:
1X 2X
N
x
N
xrpb 22
16
191
16
2659 2
294.11160
44.17
18.4SD
3. Substitute in the formula of rpb:
11616
)8(8
18.4
87.1112rpb
240
64
18.4
13.0
27.0013.0
017.0 Negligible Correlation
Testing the significance of rpb:The point biserial coefficient of correlation is
a special case of Pearson r and its interpretation is similar to each other. The t-test for rpb is used to determine their significant relationship.
Computed t = 0.064Critical t at .05 with 14 df = 2.14Decision = Not Significant
21
2
rpb
Nrpbt
2017.01
216017.0
t
999.0
064.0t
064.0t
Thank you
End of Presentation
[Simon, 05-08]Simon, Steve (2005-2008). Retrieved August 31,2009. Stats: What is a point biserial coefficient correlation?. Website: http://www.cmh.edu/stats/definitions/biserial.htm
[Vizcarra, 03]Vizacrra, Florante O., Ed. D.(2003) . Introduction To Educational Research
References