## Pages

### G-test for 2-way contingency data in R

A R function applying G-test for 2-way contingency data in R is demonstrated. Yates’ correction and Williams’ correction are also included in the output.

#### Example

##### R code
```my.2way.contingency.table <- matrix(
c(
5,0,3,12,6,
4,2,7,23,11
),
nrow = 2, ncol=5, byrow=T
)

g.test.result <- g.test.2way(my.2way.contingency.table)
g.test.result
str(g.test.result)```
##### R output
```> my.2way.contingency.table <- matrix(
+   c(
+     5,0,3,12,6,
+     4,2,7,23,11
+   ),
+   nrow = 2, ncol=5, byrow=T
+ )
>
> g.test.result <- g.test.2way(my.2way.contingency.table)
> g.test.result
Observed value:
[,1] [,2] [,3] [,4] [,5]
[1,]    5    0    3   12    6
[2,]    4    2    7   23   11
Expected value:
[,1]      [,2]     [,3]     [,4]      [,5]
[1,] 3.205479 0.7123288 3.561644 12.46575  6.054795
[2,] 5.794521 1.2876712 6.438356 22.53425 10.945205
Observed value with Yates' correction:
[,1] [,2] [,3] [,4] [,5]
[1,]  4.5  0.5  3.5 12.5  6.5
[2,]  4.5  1.5  6.5 22.5 10.5
Degree of freedom = 4
G-test:
G = 3.41127, p = 0.491497
G-test with Yates' correction:
G = 1.28744, p = 0.863503
G-test with Williams' correction:
G = 3.07349, q_min = 1.1099, p = 0.545603
> str(g.test.result)
List of 11
\$ data.observed      : num [1:2, 1:5] 5 4 0 2 3 7 12 23 6 11
\$ data.expected      : num [1:2, 1:5] 3.205 5.795 0.712 1.288 3.562 ...
\$ data.observed.Yates: num [1:2, 1:5] 4.5 4.5 0.5 1.5 3.5 6.5 12.5 22.5 6.5 10.5
\$ df                 : num 4
\$ q.min              : num 1.11
\$ g                  : num 3.41
\$ g.Yates            : num 1.29
\$ g.Williams         : num 3.07
\$ p                  : num 0.491
\$ p.Yates            : num 0.864
\$ p.Williams         : num 0.546
- attr(*, "class")= chr "g.test.2way"```