# chisq.detail: Print details of a chi-squared test In TeachingDemos: Demonstrations for Teaching and Learning

## Description

Prints out the details of the computations involved in a chi-squared test on a table. Includes the expected values and the chi-squared contribution of each cell.

## Usage

 `1` ```chisq.detail(tab) ```

## Arguments

 `tab` Matrix or table to be analyzed

## Details

This function prints out the input table along with the expected value for each cell under the null hypothesis. It also prints out the chi-squared contribution of each cell in the same pattern as the table. This shows the computations involved and one rule of thumb is to look for these values that are greater than 4 as a post-hoc analysis.

## Value

This function is used primarily for its side effect of printing the results, but does return invisibly a list with the following components:

 `obs` A matrix of the observed values, same as tab. `expected` A matrix of the expected values under the null hypothesis. `chi.table` A matrix of the chi-squared contributions of each cell. `chi2` The chi-squared test statistic.

## Author(s)

Greg Snow, [email protected]

## References

~put references to the literature/web site here ~ Moore, bps

`chisq.test`,`loglin`, `xtabs`, `table`, `prop.table`, `CrossTable` from the gmodels package.

## Examples

 ```1 2``` ```chisq.detail(HairEyeColor[,,1]) chisq.detail(HairEyeColor[,,2]) ```

### Example output

```observed
expected

Brown   Blue Hazel Green Total
Black 32     11    10     3       56
19.67  20.27  9.43  6.62

Brown 53     50    25    15      143
50.23  51.77 24.09 16.91

Red   10     10     7     7       34
11.94  12.31  5.73  4.02

Blond  3     30     5     8       46
16.16  16.65  7.75  5.44

Total 98    101    47    33      279

Cell Contributions
Brown    Blue   Hazel   Green
Black  7.73 +  4.24 +  0.03 +  1.98 +
Brown  0.15 +  0.06 +  0.03 +  0.22 +
Red    0.32 +  0.43 +  0.28 +  2.21 +
Blond 10.71 + 10.70 +  0.98 +  1.20 = 41.28

df = 9  P-value = 0

observed
expected

Brown   Blue Hazel Green Total
Black  36      9     5     2       52
20.27  18.94  7.64  5.15

Brown  66     34    29    14      143
55.74  52.08 21.02 14.16

Red    16      7     7     7       37
14.42  13.48  5.44  3.66

Blond   4     64     5     8       81
31.57  29.50 11.90  8.02

Total 122    114    46    31      313

Cell Contributions
Brown    Blue   Hazel   Green
Black 12.21 +  5.22 +  0.91 +  1.93 +
Brown  1.89 +  6.28 +  3.03 +  0.00 +
Red    0.17 +  3.11 +  0.45 +  3.04 +
Blond 24.08 + 40.34 +  4.00 +  0.00 = 106.66

df = 9  P-value = 0
```

TeachingDemos documentation built on May 1, 2019, 8:44 p.m.