Question: Using SPSS, cross-tabulate experiences of falls by treatment group and carry out Fisher's exact test.
We choose Analyze, Descriptive Statistics, Crosstabs. Put the variable 'Experience of falls' into Row(s): and 'Group' into Column(s):. Click Statistics, Chisquare, Continue. Click OK.
You should get the case processing summary and then the following:
|Experience of falls * Group Crosstabulation|
|Experience of falls||No fall||110||119||229|
|Value||df|| Asymp. Sig. |
| Exact Sig. |
| Exact Sig. |
|Continuity Correctionb|| 3.536 || 1 || .060
|| Likelihood Ratio || 5.155 || 1 || .023
|| Fisher's Exact Test || .033 || .028
|| Linear-by-Linear Association || 4.772 || 1 || .029
|| N of Valid Cases || 240
|| a 0 cells (.0%) have expected count less than 5.
The minimum expected count is 5.45.
|| b Computed only for a 2x2 table
For a two by two table, we automatically get Fisher's exact test and chi-squared with Yates' continuity correction.
We have Fisher's exact test: P = 0.03.
As usual, I have added a leading zero and for P values given only the first significant (i,e, non-zero) figure. When we do this we round as for decimal places. Here we round down from 0.033 to 0.03.
The chi-squared test is valid and gives us the same probablity, P = 0.03, after rounding up from 0.029.
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Last updated: 20 February, 2012.
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