METHOD subcommand (CROSSTABS command)

METHOD displays additional results for each statistic requested. If no METHOD subcommand is specified, the standard asymptotic results are displayed. If fractional weights have been specified, results for all methods will be calculated on the weight rounded to the nearest integer. This subcommand is available only if you have the Exact Tests add-on option installed, which is only available on Windows operating systems.

MC. Displays an unbiased point estimate and confidence interval based on the Monte Carlo sampling method, for all statistics. Asymptotic results are also displayed. When exact results can be calculated, they will be provided instead of the Monte Carlo results.

CIN(n). Controls the confidence level for the Monte Carlo estimate. CIN is available only when /METHOD=MC is specified. CIN has a default value of 99.0. You can specify a confidence interval between 0.01 and 99.9, inclusive.

SAMPLES. Specifies the number of tables sampled from the reference set when calculating the Monte Carlo estimate of the exact p value. Larger sample sizes lead to narrower confidence limits but also take longer to calculate. You can specify any integer between 1 and 1,000,000,000 as the sample size. SAMPLES has a default value of 10,000.

EXACT. Computes the exact significance level for all statistics in addition to the asymptotic results. EXACT and MC are mutually exclusive alternatives (you cannot specify both on the same command). Calculating the exact p value can be memory-intensive. If you have specified /METHOD=EXACT and find that you have insufficient memory to calculate results, you should first close any other applications that are currently running in order to make more memory available. You can also enlarge the size of your swap file (see your Windows documentation for more information). If you still cannot obtain exact results, specify /METHOD=MC to obtain the Monte Carlo estimate of the exact p value. An optional TIMER keyword is available if you choose /METHOD=EXACT.

TIMER(n). Specifies the maximum number of minutes allowed to run the exact analysis for each statistic. If the time limit is reached, the test is terminated, no exact results are provided, and the program begins to calculate the next test in the analysis. TIMER is available only when /METHOD=EXACT is specified. You can specify any integer value for TIMER. Specifying a value of 0 for TIMER turns the timer off completely. TIMER has a default value of 5 minutes. If a test exceeds a time limit of 30 minutes, it is recommended that you use the Monte Carlo, rather than the exact, method.

Example

CROSSTABS TABLES=FEAR BY SEX
 /CELLS=ROW COLUMN EXPECTED RESIDUALS
 /STATISTICS=CHISQ
 /METHOD=MC SAMPLES(10000) CIN(95).
  • This example requests chi-square statistics.
  • An unbiased point estimate and confidence interval based on the Monte Carlo sampling method are displayed with the asymptotic results.