INVESTIGATING STATISTICAL CONCEPTS, APPLICATIONS, AND METHODS

Investigation 1.5.1: Friendly Observers

(a) The subjects were assigned to group A or group B and were not told how the two groups were being treated differently.  Since the response variable (score on game) was measured objectively, there is not really a subjective rater who should be blind to group membership.

(b) EU = subjects, var1 = vested interest or not (categorical, EV), var 2 = beat threshold or not (categorical, RV)

(c) .25, .67; 6

(d)

(e) .25-.67 =-.42

We observe a smaller proportion of successes (threshold beaters) in Group A (observer with vested interest) as conjectured by the researchers.

(f) Yes, randomization may not have completely balanced out the variables in the two groups and the difference we are seeing could be based on some of these extraneous variables and not on the observer’s interest level.

(g)-(j) Answers will vary

(k) 5 or 6, half of the 11 total

(l) somewhat

(m) somewhat

(n) yes, since it would be very unlikely to be a product of an “unlucky” randomization (as judged by the dotplot, a result this extreme is unlikely to happen the randomization process alone)

(o) results will vary

(p)-(q) example results

relative frequency:  0, 0, .004, .045, .159, .299, .277, .173, .042, .001, 0, 0, 0

(r) About 5.5

(s) about .05

(u) some evidence since it’s unlikely to get that few successes in Group A when there really is no difference between the two groups.