158.796 Research Methods Assignment 3. Inferential
Statistics
Aim: Working individually, demonstrate the ability to
calculate and interpret basic inferential statistics.
1. A researcher believes that transparency
increases participation in socio-technical web site. She sets up matched web
sites with and without transparency, and gets subjects to try out both,
controlling for the order of which one they try out first. After each web site
trial, subjects answer questions on how likely they are to contribute to the
web site and join its community, where higher numbers indicate higher
likelihood. In addition, scores on the inventory are normally distributed. The
scores appear below.
Not
Transparent
Transparent
46
44
41
40
42
39
47
46
43
42
45
43
a) What statistical test should be used to
analyze these data?
b) Identify the hypotheses for this study (H_{0}
and H_{a}).
c) Conduct the appropriate analysis and give
the result.
d) Should the null hypothesis H_{0}
be rejected? What should the researcher conclude?
e) If significant, compute the effect size
and interpret this.
f) If significant, draw a graph
representing the data.
2. A researcher studies the effect of number of clicks/scroll-downs required to find viewable data to the number of negative words used in blog feedback and gets the following data:
Clicks/Scroll-downs |
|||
One |
Two |
Three |
Four |
3 |
4 |
10 |
10 |
5 |
7 |
11 |
13 |
6 |
8 |
13 |
10 |
4 |
3 |
9 |
9 |
2 |
2 |
10 |
10 |
a)
Show the ANOVA summary table.
a)
Is the result significant at .05?
b)
Perform post-hoc comparisons as necessary
c)
What conclusion can be drawn from the F-ratio
and post-hoc comparisons?
d)
Graph the means
e) What is the effect size and what does it mean?
3. a) Explain when it
would be appropriate to use a t test versus a one-way analysis of
variance.
b) If in an ANOVA the null hypothesis is
true, what value should we expect for the F-ratio? Explain your answer clearly.
Deliverables: Submit printed copy of report at
the beginning of class on the due date
Stated requirements (-5 each if not
met). Cover sheet must
have this statement of academic integrity, which is signed:
I declare that this assignment is entirely my own work and that it has
not been taken from the work of others. When the work and ideas of others have
been used in the study, that work has been properly cited in the text. This
assignment does not contain any unacknowledged work from any other source.
Signature: ________________________________
It must be written in academic style, e.g. don't
use personal pronouns. Must be spell and grammar checked. Must be printed and stapled.