Knowledge Base

Compare Data in a Line Chart

1. Select two or more data sets following the steps in Compare data.
2. Click Line Chart and select the parameters you want to include in your test.
3. Select what Comparison Type you prefer: either Side By Side or Synchrony.
4. Select what Baseline correction method and what Temporal Aggregation method you want to use and click OK.

Side by Side

If you choose the option Side By Side the absolute intensities of the facial expressions are plotted over time. Hover with your mouse over a filter icon to see what data have been selected. The example in the screenshot below comes from the FaceReader 10 - Sample project - Two stimuli. The data of the participants older than 40 (n=2) are shown as continuous lines and the data of the participants younger than 40 (n=3) as dotted lines. The graph shows that a few seconds after the start of the 'Frying insects' stimulus the younger participants had a higher valence than the older participants and it remained higher until the end of the stimulus. The reason was that the female participants found the stimulus so disgusting that they started to laugh.

Synchrony

If you choose Synchrony a correlation chart will be shown with a sliding window of 10 seconds. The screenshot below again shows the data of the FaceReader 10 - Sample Project - Two stimuli during the 'Frying insects' stimulus. The graph shows the correlation between the valence of the older participants (n=2) and the valence of the younger participants (n=3). The correlation varies quite a lot with a peak at the start of the stimulus and a smaller peak around 15 seconds after the start of the stimulus.

How Is the Correlation Calculated?

FaceReader calculates a Pearson correlation coefficient. Its value ranges from -1 to 1. 1 indicates a perfect positive linear relationship, -1 indicates a perfect negative linear relationship. 0 indicates no linear relationship at all.

Compare Data in a Correlation Table

1. Select two or more data sets following the steps in Compare data.
2. Click Correlation Table and select the parameters you want to include in your test.
3. Select what Baseline correction method and what Temporal Aggregation method you want to use and click OK.

The Correlation Table appears with for each parameter (facial expression, Valence, Arousal, etc.) the correlation between the two data sets. When you hover with your mouse over the filter icons you can see what data have been selected.

See How is the correlation calculated? for more details.

Compare Data and Visualize Insights

1. Select two or more data sets following the steps in Compare data.
2. Select Insights and select the parameters you want to visualize in your chart.
3. Set a P-value threshold to carry out a two-tailed t-test. The default value for the threshold is 10%.
4. Select what Temporal Aggregation method you want to use and click OK. Bar charts will appear for all the parameters that show significant differences.
5. Move with your mouse pointer over a filter icon to see what data have been selected.

The bar chart in the example below shows the insight when comparing Male and Female test participants during Stimulus 1. A P-value threshold of 10% was used. FaceReader shows bar charts for the parameters that are significantly different, in this case Surprised. The data selection also included Happy but the two groups did not show any significant differences for this facial expression.

Source: FaceReader 10 Reference Manual (Help), Noldus Information Technology