# Brain Imaging & Analysis Center

### Site Tools

biac:bxh_eventstats

# bxh_eventstats

The output of bxh_eventstats (PREFIX_ is the output prefix specified when running bxh_eventstats):

• PREFIX_LOG.txt – a log of all the external commands the program runs as well as some other data
• PREFIX_LOG_EPOCHAVG.txt – a log from bxh_epochavg, which does most of the work
• PREFIX_QUERIES.txt – a list of all the queries specified
• PREFIX_baselineAvg.* – an average of all the points used as baselines for every trial

For each query with a label QUERYLABEL:

• PREFIX_QUERYLABEL_avg.* – the raw averages of the time-locked epochs for each event that matched this query.
• PREFIX_QUERYLABEL_avg_percent.* – same as above, but as a percentage of the mean image.
• PREFIX_QUERYLABEL_n.* – the number of trials included (per voxel)
• PREFIX_QUERYLABEL_std.* – stanard deviation of the time-locked epochs for each event that matched this query.
• PREFIX_QUERYLABEL_std_percent.* – same as above, but as a percentage of the mean image.
• PREFIX_QUERYLABEL_zerotmap.* – 4-D result of a t-test of the _avg image against a zero time course.
• PREFIX_QUERYLABEL_cor.* – if a response template is specified using the “template” option, then this is the 3-D image representing the correlation between the time courses in the _avg image and the response template
• PREFIX_QUERYLABEL_tmap.* – the t-statistic corresponding to the above _cor image.

For each comparison specified using the “tcompare QUERY1-QUERY2” option:

• PREFIX_QUERY1_vs_QUERY2_tmap.* – the t-statistic representing the significance of the difference between the epochs matching QUERY1 and the epochs matching QUERY2.

When running bxh_eventstats_combine, its output will include:

• PREFIX_QUERYLABEL_avg.* – as above, though now these represent the mean of all the relevant _avg.* files.
• PREFIX_QUERYLABEL_avg_percent.* – as above, though now these represent the mean of all the relevant _avg_percent.* files.
• PREFIX_QUERYLABEL_tmap_zerottest.* and PREFIX_QUERY1_vs_QUERY2_tmap_zerottest.*: this represents a t-test of the relevant tmaps against zero.
• PREFIX_QUERYLABEL_pmap_weightedz.* and PREFIX_QUERY1_vs_QUERY2_pmap_weightedz.*: this represents a weighted-z comparison of the relevant tmaps (see Whitlock, “Combining probability from independent tests: the weighted Z-method is superior to Fisher's approach”, http://www.ncbi.nlm.nih.gov/pubmed/16135132 )