User`s guide

E-Prime User’s Guide

Appendix A: Timing Test Results

Page A-8

Percentage of Missed Ticks by Block

1 101 201 301 401 501 601 701 801 901

Sequential Run 1-1000

% Missed Ticks

Figure 5c. A large rhythmic time loss pattern.

Included with the RefeshClockTest program are E-DataAid Analysis forms for the following

analyses:

TicksMissedPercent.ANL

Shows the missed tick percentage by test run. This value should be below 0.1%. You may see

a larger number of misses on the initial test runs as the operating system finishes loading and

initializing the test software. If this is the only problem, it can usually be overcome by running a

short block of practice at the beginning of the experiment. If you have large spikes during

subsequent runs, it indicates that the operating system, other applications, drivers, or hardware

are taking execution cycles from the experiment. You should attempt to review the state of your

system to identify other programs or hardware that may be causing delays in the experiment.

TicksMaxMissed.ANL

Shows the maximum missed tick duration by test run. This provides a good measure of the

worst-case time delays caused by the operating system, other applications, drivers, or

hardware. It should be < 10ms.

BinCount.ANL

Shows the distribution of missed ticks across all test runs. Each bin holds the count of observed

delays of a specified duration. Bin #1 is the count of the detected ticks (1ms). Bins 2-20 are the

counts of greater delays (respectively). Bin 21 is the count of all delays greater than 20ms. Bin

22 is the count of any delay that was negative in duration (should not happen). You can use the

bin profile to determine if other programs or hardware are consuming time.

RefreshMissedPercent.ANL

Shows the percentage of missed refresh cycles (i.e., onset of vertical blank events). This value

should be less than 0.10%. If it is higher, the vertical blank simulation feature of E-Prime should

be used (this feature is on by default in E-Prime). If the rate is > 50%, you should re-run the test

using different display parameters (e.g., resolution, color depth, refresh rate) to see if the results

can be improved. If the rate cannot be reduced below 50%, you should consider changing the

video display adapter or possibly not using the computer for experiments requiring short

duration, precise visual stimulus presentations.