27. Experiment 1
2
⨉
2
0.15 Variability 0.4 Variability
Variability
Upper
Variability
Lower
All within subject
140 Participants
48 trials per participant
28. 140 Participants
Experiment 1 Experiment 2
2
⨉
2
0.15 Variability 0.4 Variability
Variability
Upper
Variability
Lower
2
⨉
2
0.4 Variability
Variability
Upper
Variability
Lower
0 Variability
⨉
3
Line Point Arc Point
All within subject Variability and upper vs lower within subject
Mark type between subject
48 trials per participant
420 Participants
48 trials per participant
29. Hypotheses
H1: Estimation error will be signi
fi
cantly di
ff
erent than zero.
H2: There will be signi
fi
cantly more estimation error for trials with higher
variability compared to lower variability.
H3: Estimation error will be observed in the direction of the increased variability.
H4: There will be signi
fi
cantly more estimation error for trials with higher
variability than no additional variability.
H5: The least variability-overweighting will occur in graphs with points that are
equally spaced along the x-axis.
38. Additional analyses in the paper
We asked participants for their
strategies and looked at how
strategies a
ff
ect estimation error.
We can model estimation error for
arbitrary line graphs based on the
true average and the average of
the points drawn along the arc.
39. Limitations of unbalanced and few stimuli
Thanks to Steve Haroz for pointing out this issue!
We used the same 12 seeds for each participant rather than a new seed for
each stimulus. This introduces biases.
40. Limitations of unbalanced and few stimuli
Thanks to Steve Haroz for pointing out this issue!
9/12 stimuli seeds have true averages below 0.5
➡ when using responses of 0.5, the error distributions ideally overlap
These should be the same
Our normalization (Section 4.2)
ensures that these are the same
41. Materials available at osf.io/aupbk/
Average Estimates in Line Graphs are
Biased Toward Areas of Higher Variability
domoritz@cmu.edu or vis.social/@dom