95% conﬁdence interval
Unformatted Attachment Preview
This dataset contains results from an experiment in visual perception using random dot sterograms, such as that shown below. Both images appear to be composed entirely of random dots.
However, they are constructed so that a 3D image (of a diamond) will be seen, if the images are
viewed with a stereo viewer, causing the separate images to fuse. Another way to fuse the images is
to fixate on a point between them and defocus they eyes, but this technique takes some effort and
An experiment was performed to determine whether knowledge of the form of the embedded
image affected the time required for subjects to fuse the images. One group of subjects (group
NV) received either no information or just verbal information about the shape of the embedded
object. A second group (group VV) received both verbal information and visual information (e.g.,
a drawing of the object).
1. Find the 95% confidence interval for (µN V − µV V ). (Use the fact that for
the 95% CI, t∗34 = 2.032, rather than closest value in Table D, i.e., t∗30 = 2.042
and carry calculations to 4 significant digits.)
2. Use the 95% confidence interval to test the null hypothesis visual information does not affect the time to fuse the images (µN V − µV V ).
3. The confidence interval provides more information than whether or not
the null of no difference is rejected. Give two other claims for (µN V − µV V ),
one that is rejected and one that is not rejected by these data.
Purchase answer to see full