Question

Scenario: A psychologist has been studying the effect of deterioration of memory over time. He has been interested in how memory for particularly startling events, called flashbulb memories, might differ from memory for everyday events. He asked college students to try to remember all the circumstances of an ordinary event (such as meeting a friend) and then immediately after the event to fill out a survey about the details of the event. He knew from vast amounts of prior research that the average proportion of details accurately remembered 1 year later is 0.85, with a standard deviation of 0.04. When the Persian Gulf War began in January 1991, he asked students to do the same task of filling out the survey about the details of the beginning of the bombing. He thought that the proportion of details remembered 1 year later would be higher. The following are the proportions correct for 22 students:

0.81 0.65 0.93 0.78 0.79 0.87 0.86 0.83 0.87 0.85 0.77

0.86 0.80 0.81 0.82 0.83 0.87 0.85 0.85 0.84 0.83 0.90

a) Is this observational research or a true

experiment? What is the clue in the

scenario?

b) Write H0 and H1.

c) Use the critical-value decision rule:

tell whether you reject or retain H0 and why.

d) Is the proportion of details remembered for

flashbulb memories significantly different

from the proportion of details remembered

for ordinary events? Explain and support your

position with the correct z-score reporting

convention.

Answer 1

a) This is observational research as the researcher is simply collecting data based on what is seen and heard and infill out a survey about the details of the event.

b)

c)

We have evidence that the proportion of details remembered for flashbulb memories significantly different from the proportion of details remembered for ordinary events