james c. :mccroskey, william holdridge, and]. kevin … · james c. :mccroskey, william holdridge,...
TRANSCRIPT
AN INSTRUMENT FOR MEASURING THESOURCE CREDIBILITYOF BASIC SPEECHCOMMUNICATION INSTRUCTORS
James C. :McCroskey,William Holdridge, and]. Kevin Toomb
;\ NU~IBER of studies have been re-~ ported which have investigated thedimensionality of the source credibilityconstruct and provided suggested scalesfor the measurement of credibility.!Most of these studies have focused on the
credibility of public figures and haveused college students as subjects. Nonehave specifically looked at teachers.Tucker2 has noted the error in assumingthat these scales can be used for other
types of sources (such as teachers). AsTucker points out, varying the subject-type or source-type may cause the di-mensionality of source credibility tochange. Students may not respond toteacher-sources on the same dimensions
on which they respond to public figuresand, even if the same dimensions of re-
Mr. McCroskey is professor and chairman ofthe Department of Speech Communication atWest Virginia University. Mr. Holdridge is aaoctoral candidate in Speech Communicationat the University of Illinois. Mr. Toomb is adoctoral candidate in Communication at FloridaState University.
1 \\'. T. Norman, "Toward an AdequateTaxonomy of Personality Attributes: ReplicatedFactor Structure: in Peer Nomination Person-ality Ratings," Journal of Abnormal and SocialPsychology, 66 (June 1963), 574-583; J. C. Mc-Croskey, "Scales for the Measurement of Ethos,"SPeech l1,fonof{raphs, 33 (March 1966), 65-72; D.Markham, "The Dimension:; of Source Credi-bility of Television Newscasters," fournal ofCommunication, 18 (March 1968), 57-64; J. L.Whitehead, Jr., "Factors of Source Credibility,"Quarterly Journal of Speech, 54 (February 1968),59-03; D. K. Berlo, J. B. Lemert, and R. Mertz."Dimensions for Evaluating the Acceptance. ofMessa~e Sources," Public Opinion Quarterly,33 (Winter 1969), 563-576.
2 R. K. Tucker, "On the McCroskev Scalestor the Measurement of Ethos," Centrdl StatesSPeech Journal, 22 (Summer 1971), 127-129.
sponse are present, the best scales formeasuring those responses may vary. Re-cent research on types of sources otherthan teachers indicates that the caution
requested by Tucker is appropriate.3 Thedimensionality of source credibility canfluctuate from one type of source to an-other, and even in regard to the same
dimension (competence, for example),the scales that best measure that dimen-
sion may not be the same for two differ-ent source-types.
It is essential, therefore, that if we
wish to measure teacher credibility, aninstrument must be developed specifical-ly for that purpose. The current researchwas designed to achieve that end.
METHOD
Scales. This investigation employed 46semantic differential-type scales repre-senting the dimensions of source credi-
bility observed in the previously citedresearch by Norman, McCroskey, Mark-
3J. C. McCroskey,M. D. Scott, and T. J.Young, "The Dimensions of Source Credihilityfor Spouses and Peers," paper presented at the'Vestern Speech Communication Association con-vention, Fresno, 1971; J. C. McCroskey, T.Tensen. C. Todd, and J. K. Toomb. ":\-Ceasure-ment of the Credibility of Or7,anization Sources,"paper presented at the Western Speech Com-munication convention, Honolulu, 1972; .T. C.McCroskey, T. Jensen, and C. Todd. "The Gen-I'ralizabilitv of Source Credibilitv Scales forPublic Fig-ures," paper presented at the SpeechCommunication Association convention. Chicag;o.1972; .T. C. McCroskey, T. Jensen. and C. Va.lencia, "Measurement of the Credibilitv ofSpouses and Peers," paper presented at" theInternational Communication Association con-\'ention, Montreal, 1973.
MEASURI::\G SOURCE CREDIBILITY 27
ham, and BerIo, Lemert, and Mertz.In a pilot study which led to the currentinvestigation, all of the scales with highloadings on factors from these studieswere included, a total of 53 items. After
the pilot phase of the study, which in-vestigated four source-types, 11 itemswere omitted from the original itempool. The items omitted failed to have
a satisfactory factor loading on any factorfor any source-type.-1 Four additionalitems were added to the pool after thepilot study. These scales were believedto be related to factors observed in the
pilot study which had only two or threeitems with satisfactory loadings and forwhich there were no additional items in
the original pool that appeared to berelated."
Teachers-Subjects. The first sample inthis study included 642 students in the
basic course in speech communication at
Illinois State University. At the time thatthe study was conducted, this course was
taught by means of mass lectures with ac-
companying laboratory sections. There
were nine senior-faculty lecturers in the
class. Each student involved in the study
responded to one (randomly determined)
lecturer. The second sample in the study
4 A ,atisfactory loading was considered tobe .60 or higher on one factor with no secondaryloading hig-her than .40.
;; The scales employed were: intelligent-un-intclligent, sociable-unsociable, nervous-poised,cheerful-gloomy. tense-relaxed, sinful-virtuous,bc Iievab le- unbelievab Ie. good -na tured -irritable.intcl:ectUal-narrow. cooperative-ne!f<ltivistic. out-j!oin~-withdrawn, dishonest-honest. meek-aggres-~ive. valuable-worthless, selfish-unselfish. calm-anxiou'. inexperienced-experienced, verbal-quiet,10gical-iIlog-ical. undependable-responsible. head-~trong-mild, friendly-unfriendly. confident-lacksconfidence. untrained-trained, unsympathetic-sympathetic. admirable-contemptible. awful-nice,CIualified-unquaIified, extroverted-introverted.just-unjust. unpleasant-pleasant. timid-bold. en-ergetic-tired. good-bad. repulsive-attractive. un.informed-informed. composed-excitable. incom-petent-competent, cruel-kind, talkative-silent. ex-pert-inexpert, passive-active. impressive-unim-pressive. adventUrous-cautious. crude-refined.and reliable-unreliable.
also involved students in the basic
speech communication course at IllinoisState. The 663 subjects in this part ofthe study responded to their laboratoryinstructor. Thirty-seven sections of thecourse were employed, each with a dif-ferent teacher. The third part of thestudy involved 5i5. students in the basicspeech communication course at the U ni-versity of Illinois. At the time that thisstudy was conducted, each section of thecourse was taught independently, withthe syllabus being prepared by the in-dividual instructor. Thirty-five sections ofthe course, with 19 separate instructors,were involved. All three samples weretested during the fall semester, 1971-72.
Data Analyses. The data from the threesamples were analyzed separately. Thesemantic differential data were submitted
to principal component factor analysesand varimax rotation. Unity was insertedin the diagonals and an eigenvalue of 1.0was established as the criterion for termi-nation of factor extraction. For an item
to be considered loaded on a resultingfactor, a loading of .60 or higher was re-quired with no loading of .40 or higheron any other factor.6 For a factor to be
considered meaningful, the requirement
was that two scales must have satisfactoryloadings on that factor.
All data analyses were performed with
the cooperation of the computer centersat Illinois State Universitv and "Vest Vir-I
ginia University.
6 These loading criteria are relatively con-servative and were chosen for that reason. Incommon research practice raw scores ratherthan factor scores are usually used from datag-enerated by semantic differential-type instru-ments. Inclusion of items with less pure loadingsresults in correlated dimension scores eventhough the dimensions are the product ofortho~onal factor analysis. More liberal criteriawould indicate more items that could be usedto measure obtained dimensions, but the reosuIting dimension scores would be increasing-Ivinterrelatcd. Use of such scores, consequently,would introduce svstematic error into the re-~(:arch. and should' be avoided.
THE SPEECH TEACHER
the scales with satisfactory loadings. (See
Table 2).Factor analyses of the data from the
students in the third sample (those re-
sponding to instructors teaching inde-pendent sections at the University of Illi-nois) resulted in a four-factor solutionwhich accounted for 60 per cent of thetotal variance of the items with satisfac-
tory loadings. These factors were labeled"Sociabili ty-Character," "Composure,""Extroversion," and "Competence."
28
REsULTS
Factor analysis of the data provided bythe subjects in the first sample (those re-sponding to mass lecturers at lllinoisState University) indicated the presenceor five dimensions of response. These di-mensions were labeled "Character," "So-
ciability," "Composure," "Extroversion,"and "Competence." These factors ac-counted for 62 per cent of total varianceof the scales with satisfactory loadings.
(See Table 1).Factor analysis of the data provided in
the second sample (those responding totheir laboratory instructors at IllinoisState University) also yielded five factorswhich were labeled in the same manneras above. These five factors accounted
for 60 per cent of the total variance of
DISCUSSION
The results from the three samples in
this study suggest the presence of five di-mensions of source credibility for teach-ers. For the first two samples, the factor
analyses resulted in five clear dimensions
TABLE 1
ROTATED FACTOR LOADINGS FOR MASS LECTURERS
FactorItem Character Sociability Composure Extroversion Competence
-
In telIigen t-UnintelIigent .01 .15 -.11 -.17 .73
Sociable-Unsociable .20 .61 -.16 -.22 .34:
ervous-Poised -.13 -.09 .68 .36 -.13
Cheerful-Gloomy .11 .68 -.13 -.30 .34
T ense-Rela.xed -.11 -.15 .70 .39 -.16
Sinful-Virtuous -.66 .09 .11 -.01 -.12
Believable-Unbelievable .19 .34 -.15 -.03 .69
Good-natured. Irritable .24 .64 -.13 -.18 .39
Intellectual- Narrow .12 .30 -.17 -.09 .73
Outgoing-Withdrawn .15 .34 -.12 -.69 .21
Dishonest-Honest -.65 -.01 .14 .08 -.34:
Meek-Aggressive -.10 -.01 .17 65 .02
Valuable- Worthless .30 .25 -.14 -.19 .71
Selfish-Unselfish -.71 -.21 .01 .01 -.19
Calm-Anxious .04 .13 -.77 -.19 .26
Verbal-Quiet -.06 .11 -'-.14 -.73 .14
Logical-illogical .22 .25 -.20 -.16 .69
Confiden t-Lacks Confidence .06 .10 -.39 -.65 .30
Qualified-Unqualified .19 .10 -.15 -.28 ,..-.1::J
Extroverted-Introverted -.02 .15 -.09 -.71 .18
Timid-Bold -.11 -.03 .17 .65 .06
Energetic- Tired .23 .19 .01 -.68 .29
Composed-Excitable .08 .00 -.73 -.03 .19
Incompetent-Competent -.32 -.13 .10 .18 -.64
Cruel-Kind -.60 . -.33 -.04 .04 -.32
Talkative-Silent -.07 .12 -.08 -.75 .10
Expert-Inexpert .22 .00 -.12 -.29 .77
Impressive- Unimpressive .35 .21 -.18 -.27 .62
Adventurous-Cautious .09 .02 -.10 -.69 .21
Reliable. Unreliable .34 .16 -.09 -.12 .74
Eigenvalue 2.60 2.12 2.65 5.16 6.15
Variance .09 .07 .09 .17 .20
Eigenvalue Total = 18.85Variance Tota! :: 62
MEASURING SOURCE CREDIBILITY 29
TABLE 2ROTATED FACTOR LOADINGS FOR SMALL SECTION INSTRUCTORS
that were highly similar. The resultsfrom the third sample, while indicatingthe presence of only four dimensions,replicated the earlier results for the di-mensions of "Composure," "Extrover-sion," and "Competence." The only devi-ation indicated by the results from thethird sample was the collapse of the"Character" and "Sociability" dim en-siems into one dimension. Since in most
cases it is better to have too JIluch in-
formation about teacher credibility thantoo little, it would seem best to consider
these results as indicative of the presenceof five dimensions of teacher credibility.In some cases it would appear that"Character" and "Sociability" can oper-ate independently, while in other casesthey may operate conjointly. The worstthat can happen as a result of treatingthe two dimensions as separate if in factthey are not, is the obtaining of twohighly correlated scores. However, if onewere to treat the two dimensions as one
when in fact they were operating inde-pendently, the obtained score would bequite meaningless.
The instrument that is recommended
for measuring teacher credibility appearsin Table 4. However, if one were inter-ested in including more scales for a di-mension than are present among therecommended scales, additional scalescould be selected from Tables 1-3 that
would be appropriate for teachers un-der varying types of instructional pat-terns (mass lectures, laboratOry sections,or independent sections).
'\Vhen the instrument in Table 4 is
used, the scales can be rearranged in ran-dom order, and the polarity determinedrandomly. The numbers in the spaces inTable 4 are included for illustration on-
ly, and should not appear in normal use.They indicate how a mark in a givenspace should be scored. Scales 1-2 mea-sure "Competence," 3-6 measure "Extro-version," 7-8 measure "Character," 9-11
FactorItem Character Sociability Composure Extroversion Competence
Intelligent-Unintelligent .05 .39 -.21 .-.09 -.61Sociable-Unsociable .26 .72 -.06 -.24 -.25Nervous-Poised -.23 -.10 .62 .24 .24Cheerful-Gloomy .16 .66 .01 -.22 -.22Tense-Relaxed -.27 -.06 .63 .33 .24Good-natured -Irritable .28 .73 -.09 .-.16 -.26Cooperative- Negativistic .31 .62 -.18 -.04 -.34
Jeek-Aggressive -.22 -.01 .02 .68 .14Selfish-Unselfish .60 -.11 .14 .06 .26Calm-Anxious .11 .08 -.74 -.03 -.22Inexperienced -Experienced <)" -.04 .16 .29 .66-._:JVerbal-Quiet -.01 .33 -.04 -.63 -.06Friendly-Unfriendly .39 .67 -.08 -.23 -.23Untrained-Trained -.30 -.08 .13 .24 .72Unsympathetic-Sympa thetic -.66 -.25 .07 .02 .25Awful-Nice -.62 -.35 .08 .03 .32Qualified-Unqualified .24 .34 -.14 -.13 -.73Timid-Bold -.22 .01 .09 .74 .20Composed-Excitable -.05 .09 -.68 .14 -.03Cruel-Kind -.61 -.33 .09 .03 .35Talkative-Silent -.06 .32 .03 -.64 -.05Expert-Inexpert .03 .28 -.13 -.20 -.67Reliable-Unreliable .15 .36 -.08 -.06 -.67
Eigenvalue 2.45 3.22 2.02 2.41 3.69Variance .11 .14 .09 .10 .16
Eigenvalue Total = 13.96 Variance 'lUlal - 00
30 TH;E SPEECH TEACHER
TABLE 3FACTOR LOADINGS FOR INDEPENDENT SECTIONS
Scales
Sociable- UnsociableN ervous- PoisedCheerful-GloomyTense- RelaxedGood-N atured- IrritableCoopera tive- N egati visticMeek-AggressiveValuable- WorthlessCalm-AnxiousVerbal-QuietFriendly-UnfriendlyU nsympathetic-Sym patheticAdmirable-Con tem p tib IeAwful-NiceJust-UnjustC npleasant- PleasantTimid-BoldTalkati ve-Silen tExpert-InexpertCrude- RefinedReliable- Unreliable
EigenvalueVariance
Total Eigenvalue = 12.53
'TABLE 4RECOMMENDED TEACHER CREDIBILITY MEASURE
Illstructions: The following are a series of attitude scales. You are asked to evaluate yuur in-structor in terms of the adjectives on each scale. For example, if you think your instructOr isvery tall you might mark the following scale as below:
Tall: X :-:-:-:-:-:-: Short
Of course, if you consider your instructor to be shoner you would mark your "X" nearer the"short" adjective. The middle space on each scale should be considered "ueutral." ~Iarkthis space if you feel neither adjective on the scale applies to your instructor or if you feelboth apply equally.
measure "Composure," and 12-14 mea-sure "Sociability."
teacher credibility should be based on
three criteria: the reliability of the in-strument, the validity of the instrument
as a measure of teacher credibilitv, and,
the ability of the instrument to predict
Evaluation of the lVIeasure
Evaluation of the suggested measure of
FactorsCharacter-Sociability. Extroversion Competence Composure
.71 .26 .05 -.15
.25 .23 .13 -.73
.73 .17 .Ol -.18
.36 .25 .10 -.il
.82 -.01 .07 -.17
.76 .05 .26 -.09
.06 -.67 .03 -.06
.67 .17 .37 -.12
.17 .03 .18 .67
.IS .69 .04 -.07
.79 .16 .12 -.II-.68 -.04 -.33 -.07
.70 .12 .35 -.IS-.75 .02 -.31 -.13
.68 .OS .37 -.10-.68 .13 -.33 -.12
.01 -.71 .21 .05
.03 .65 .24 -.02
.14 -.39 .69 -.14
.21 .01 -.61 -.25
.30 .10 .63 -.12
6.21 2.32 2.21 1.79.30 .11 .11 .09
Total Variance = .60
My Instructor in This Course1. Expert : 7 : 6 : 5 : 4 : 3 : 2 : 1 : Inexpert2. Unreliable : 1 :2:3:4:5:6:7 : Reliable3. Meek : I : 2 : 3 : 4 : 5 : 6 : 7 : Aggressive4. Verbal : 7 : 6 : 5 : 4 : 3 : 2 : 1 : Quiet5. Bold : 7 : 6 : 5 : 4 : 3 : 2 : 1 : Timid6. Silent : 1 : 2 : 3 : 4 : 5 : 6 : 7 : Talkative7. Unselfish :7:6:5:4:3:2: 1 : Selfish8. Kind : 7 : 6 : 5 : 4 : 3 : 2 : I : Cruel9. Poised : 7 : 6 : 5 : 4 : 3 : 2 : 1 : Nervous
10. Tense : 1 : 2 : 3 : 4 : 5 : 6 : 7 : Relaxedll. Anxious : 1 : 2 : 3 : 4 : 5 : 6 : 7 : Calm12. Unsociable : 1 : 2 : 3 : 4 : 5 : 6 : 7 : Sociable13. Cheerful : 7 : 6 : 5 : 4 : 3 : 2 : 1 : Gloomy14. Irritable : 1 : 2 : 3 : 4 : 5 : 6 : 7 : Good-natured
:\-IEASURI:'-1G SOURCE CREDIBILITY
student learning. vVe shall consider eachof these in turn.
Reliability. The reliability of this in-strument was tested in a follow-up study.During the spring semester, 1971-72, 948students completed the instrument re-ported in Table 4. Each student re-sponded to one section instructOr in thebasic speech communication course at
Illinois State University. Thirty-six dif-ferent instructors were evaluated. In-
ternal reliability estimates (based onthe Hoyt procedurei) for the five (limen-sions of response ranged from a low of.91 for "Competence" to a high of .94for "Extroversion." Forty-six studentswere involved in a test-retest situationwith a two week interval between the
testing sessions. Reliability estimates forthe five dimensions ranged from .82 for"Competence" to .86 for "Sociability."These reliability estimates are well with-in the range normally considered satis-factory.
Construct Validity. Since there was no
established measure of teacher credibilityavailable against which to compare thepresent measure, no statistical estimate.of the validity of the instrument as a
measure of teacher credibility was possi-ble. Consequently, the construct or facevalidity of the measure must be consid-
ered. Since the pool of items upon whichthe instrument was built represented awide variety of previously used scales forsource credibility, there is reason to be-
lieve that the item pool. and thus theresulting factors and scales, are repre-sentative of the credibility construct. Inaddition, a subjective examination ofthe resulting factors and chosen scales
.. suggests face validity. All of the dimen-
sions appear related to credibility, and
each of the scales seems to be logically as-
i C. Hovt. "Test Reliahilitv Estimated bv.\nalysis o( Variance." PS'Yc/1071ietrika. (j (June1941), 153-WO.
31
sociated with the factor on which it was
highly loaded.Predictive Validity. Since the major
purpose underlying the present study wasthe development of a valid means ofteacher evaluation based on student re-
sponse, the most important test of thevalidity of the resulting instrument iswhether it is a significant predictor ofstudent learning. This question has beensubjected to two direct tests.
The first test was based on the assump-tion that a student's willingness to signup for another course from an instructOrand/or his willingness to recommend thecourse to a friend are related to infor-
mation acquisition.s The subjects in thetwo primary Illinois State samples, thosewho responded to mass lecturers and
those who responded to laboratory in-structOrs, were asked two additional
questions designed to determine howlikely they were to expose themselvesvoluntarily again to the instructOr andwhether they would recommend that a
friend of theirs do so. The questionsasked were: "If you had room in yourschedule for an elective course, how like-
ly would it be that you would sign up for
8 The rationale for this assumption is two-fold. First, no information can be acquired bya student from a teacher unless the student iswilling to expose him or herself to communica-tion from that teacher. Mere exposure, ofcourse, will not guarantee that learnin~ willoccur. However, non-exposure will ~uaranteenon-learning. Considerable research has indi-cated the existence of the selective exposurephenomenon (see E. Katz, "On Reopening theOuestion of Selectivity in Exposure to MassCommunication," in R. P. Abelson et aI.,Theories of Cognitive Consistency: A Sourcebook,Chicago: Rand McNally, 1968). Second, al-though most of the research in this area hasfocused on receivers' attitudes on message topicsas causal agents, recent research has indicatedrhat a highly reliable predictor of selective ex-posure is source credibility (see L. R. Wheeless,"The Effects of Attitude, Credibility, and Homo-philv on Selective Exposure to information,"paper presented at the International Communi-cation Association convention, Montreal. 19i3).While the present research focused on projectedfuture exposure. later research should considerdirect effects on present exposure. such as classattendance rates.
32 TJiE SPEECH TEACHER
another course with this instructor?" and
"Would you suggest that a friend ofyours sign up for a course from this in-structor?" The subjects were asked to re-spond to an eleven-step continuumbound by "very likely" and "very un-likely."
Table 5 reports the observed correla-tions between the credibility dimensions
and these indications of projected ex-.posure and recommended exposure. Allof the observed correlations were statisti-
cally significant (p <.01). High scores oneach dimension were associated with
g,eater likelihood of exposure. Multiplecorrelation analyses indicated that from
45 to 58 per cent of the variance in pre-jected exposure could be predicted bycredibility. "Competence" and "Sociabil-ity" were consistently the best predictors.These results, therefore, indicate the va-
lidity of the credibility measure devel-oped in the present study for the predic-tion of probable information acquisitionunder exposure conditions permittingvoluntary choice. Students indicate a de-
sire to take courses from teachers per-ceived as credible, as measured by thepresent instrument, and to avoid coursesfrom teachers perceived as less credible.
The second test of the predictive valid-ity of the instrument was related to in-
formation acquisition under conditions
of non-voluntary exposure. During thefall semester, 1972-73, 118 students in the
basic course in speech communication atWest Virginia University completed theteacher-credibility instrument in refer-ence to their course instructors.9 Ten in-structors were involved. The students
were exposed to an experimental messageby their respective instructors in thecontext of a regular class period. Themessage was related to the course, andthe information induded was not avail-
able from any other source. The studentswere not forewarned that they would betested over the material. However, their
immediate recall was measured by adoze-procedure testlO immediately afterexposure to the message.
Analysis of the results indicated thatthe only credibility dimension signifi-cantly correlated to immediate recall was"Competence." These results, then, pro-vide only marginal support for the pre-dictive .validity of the instrument. Itshould be noted, however, that there was
9 The results reported here are part of abroader stUdy. For a report of the completestudv, see L. R.. Wheeless, "The Relationship ofCou;se Attitudes, Instructor Credibility, Attrac-rion. and Homophily to Immediate Recall andStudent-Instructor Interaction," paper presentedat the .speech Communication Association con-vention, New York, 1973.
10This test included 54 deleted words. Thesplit-half reliability of the test (corrected) was.92.
TABLE 5CORRELATIONS BETWEEN CREDIBIUTY DIMENSIONS
AND VOLUNTARY EXPOSURE AND RECO:\[ME~DED EXPOSURE
CredibilityDimension
CompetenceExtroversionComposureCharacterSociability
Multiple Correlation
Per cent of VariancePredictable
Voluntary Exposure Recommended Exposure(Take Another Course) (Friend Take Course)
Mass Laboratory Mass LaboratoryLecturers Instructors Lecturers Instructors
.62 .55 .71 .51
.40 .31 .36 .27
.37 .34 .38 .33
.44 .48 29 .50
.62 .71 .60 .53
.73 .76 .76 .67
53 58 58 45
MEASURING SOURCE CREDIBILITY 33
very little variance found in the credi-bility scores observed in this study. Es-sentially, each teacher was perceived ashighly credible on each dimension byalmost all of the students. This lack ofvariance could account for the low and
nonsignificant correlations observed. Inaddition, of the approximately 200 stu-dents who should have been present forthe study, only 118 were actually in at-tendance. The missing 40 per cent mayhave seen the instructors as much less
credible and thus may have chosen notto expose themselves to the instructorthat day. This explanation, of course, isspeculative, but the results discussedabove concerning credibility and ex-posure would indicate the explanationmay have merit. Nevertheless, at thispoint only marginal support is available
for the predictive validity of the instru-ment with respect to immediate recall ofinformation.
Conclusions
The results of this investigation indi-cate that the teacher-credibility instru-ment that was developed is a reliablemeasure, has satisfactory construct andface validity, and has predictive validityat least for projected future exposure.The instrument is potentially useful tothe speech communication instructor forpurposes of teacher evaluation whenstandardized, criterion based measures ofstUdent learning are not feasible.ll
11For an excellent discussion of the desira-bility of using stUdent-generated teacher evalu-ations, see C. N. Wise, "Student Ratings ofTeachers: A Perspective for Speech Communi-cation," Western Speech, 37 (Fall 1973), 196-203.