7April2010Lecture
07/04/201009:02:00
TwoStepFlowandOpinionLeaders
Mostcitationscomefromthesetworeadings:
Katz,E(1957)
o PublicOpinionQuarterly
Katz,E.&Lazarsfeld,P.(2006)(1stEd.In1955)
o PersonalInfluence
PartIIoftheBook
o TheDecaturstudyfourareasofdec
Methods for Measuring Media Effects
Lab Experiments
Measurement Tool: selfreports of participants, observations of participants actions,
assessments of activities performed by an individual, physiological or cognitive
assessment
Advantages: the best soci
The Communication of Ideas
9 1 h h C Ci 6 SSIlDlC to Control.
yc I 81.1 StS it is P0 1
6 ps 0 Ogist, h 1 9 I
11ng to a degree, . . .r
I and mm . immiae
vocabuiall that though care in the use Of words maym re es
 .  a 
mZs 11111103 difculties, understa
ON THE USE OF THE MASS MEDIA FOR IMPORTANT THINGS *
ELIHU KATZ
MICHAEL GUREVITCH
HADASSAH HAAS
The Hebrew University of Jerusalem
and
The Israel Institute of Applied Social Research
American Sociological Review 1973, Vol. 38 (April):164181
The mass media
and:
d
)
(e)
(e
(e)
d
=2 + 3=
23
34
(e)
(e)
= 3 + 3 + 231 = 2 2
Problem 4.9 :
Theenergyofthesignalwaveforms
E =
s (t) 2 dt =
=
(t)is:
1
2
M
s (t)
m
M
s (t)dt + 2
M
M
1
1 M
s (t)sl (t)dt
M
sm (t)sk (t)dt 1
M
k=1
=E+
1
M
sk (t) dt
k=1
k=1 l=1
2
s (t)s (
CHAPlflcfw_
5:
Ol'TIMU\1
RE<TIVf.RS
FOR TH[
ADDITIVE
WflJTf. GAUSSIAN
NOISE
CliA~El
245
rule based on the observation vector r. For this development, we assume that there is
no memory in signals transmitted in successive signal intervals.
We wish to desig
Problem 4.11 :
(a) As an orthonormal set of basis functions we consider the set
f (t) = 1 1 0 t <
1
0 o.w
1 2 t<
f (t) = 3
f2 (t) =
1 1 t< 2
0 o.w
1 3 t< 4
f4 (t) =
0 o.w
0 o.w
In matrix notation, the four waveforms can be represented as
s (t)
f (t)
0.45
0
.
4
0.35
0
.
3
0.25
0
.
2
0.15
0
.
1
0.05
0
5
4
3
2
1
0
5
1
2
3
4
f
T
(c) The 3db frequency for (a) is :
2
sin f3db T
1
(f3db T )2 =
2
f3db = 0.4
4
T
(where this solution is obtained graphically), while the 3db frequency for the sinusoidal
p
Thus, the minimum distance between any pair of vectors is dmin
= 5.
Problem 4.12 :
As a set of orthonormal functions we consider the waveforms
f (t) = 1
1 0 t <
1
1 1 t < 2
f2 (t) =
1 2 t < 3
f3 (t) =
0 o.w
0 o.w
0 o.w
The vector representation of the sig
Problem 4.15:
1
We have that uu (f ) =
G(f )2 ii (f ) But E(In ) = 0, E In 2
= 1, hence : ii (m)
=
1, m = 0
. Therefore :
(f ) =
1
ii
uu
0, m = 0
(a) For the rectangular pulse
:
G(f ) =
AT
(f ) = G(f ) 2 .
1

T
sin f ej 2f T /2 G(f )2 = A2 T sin 2
Problem
4.14 :
[a g(t 2nT ) jb g(t 2nT T )]
u(t) =
n
n
n
(a) Since the signaling rate is 1/2T for each sequence and since g(t) has duration 2T, for
any time instant only g(t 2nT ) and g(t 2nT T ) or g(t 2nT + T ) will contribute to
u(t). Hence, for 2nT t
The last result is expected, since the dimensionality of the vector space generated by
these signals is 3. Based on the basis functions (g2 (t), g3 (t), g4 (t) the basis
representation of the
signals is :
s4 = 0, 0,
E =
34
s3 = 0, 8/3,
3 E3 = 3
1/
s2 = 0
0
1
0
0
1
1
1
0
The signal points that may be transmitted at times t = 2nT n = 0, 1, . are given with
blank circles, while the ones that may be transmitted at times t = 2nT + 1, n = 0, 1, .
are given with lled circles.
Problem
4.20 :
The autocorrelation f
For u(t) to be widesense stationary, we must have : E [u(t)] =constant and uu (t, t+ ) =
uu ( ). We note that if E(X ) = E(Y ) = 0, and E(XY ) = 0 and E(X 2 ) = E(Y
2
),
then the above requirements for WSS hold; hence these conditions are necessary.
Conv
STUDY GUIDE FOR EXAM THREE
FALL, 2013
PROFESSOR JORDAN
October 30  Youth Audiences and Educational Opportunities
Reading: Ch. 31 Children and Adolescents
How are youth audiences different from adult audiences in terms of the effect media can
have? reali
STUDY GUIDE FOR EXAM 1
COMM 125
INTRO TO COMMUNICATION BEHAVIOR
Professor: Amy Jordan
Teaching Fellows: Devon Brackbill, Andrew Daniller, Eleanor Marchant
August 2830Conceptualizing Effects
Readings: Textbook Chapter 1; Valkenberg and Peter The Different
STUDY GUIDE FOR EXAM 2
COMM 125
INTRO TO COMMUNICATION BEHAVIOR
Professor: Amy Jordan
Teaching Fellows: Devon Brackbill, Andrew Daniller, Eleanor Marchant
October 2Uses and Gratifications
Reading: Chapter 10, Uses and Gratifications: An Evolving Perspecti
knowbasictheoriesandfindings,measures
knowimportanttimeperiods
TEXTBOOK READINGS
Ch 1 Understanding Media Effects
Social scientists are interested in
The persuasive powers of mass mediated messages (ads, propaganda,
comm. campaigns)
The impact of new
COMM125
4/17/09 Recitation Notes
Reality TV Article
Realitybased TV
Programming w/ real people while they live out their real life
People are portraying themselves
Real living environment, supposedly not scripted
Events placed in a narrative contex
Pryor article
Does more media content cause/reinforce knowledge gaps?
Back in the day, people had limited viewing options
Only had a few major broadcast channels
Hypothesis that TV is a knowledge leveler
Initially, TV was a knowledge leveler
B/c TV
INTRO TO COMM COMM 125 PROF JORDAN (BLACKBOARD)
Overview:
Introduction and Overview to Comm
Conceptual and Methodological Issues how is it studied?
Comm Effects Theories effects that explain the mechanism, theories
Media Effects role of media and its