Latent Variable Interaction Research |
Updated
11/23/09
(Previous updates
11/10/09, 9/5/09, 8/26/09, 5/12/09, 4/3/09, 3/28/09,
2/9/09, 9/6/08, 7/21/08, 4/23/08, 1/30/08, 1/14/08, 10/25/07, 7/14/07,
6/14/07, 4/26/07, 2/3/07, 12/11/06, 11/29/06, 5/12/06, 2/22/06, 1/30/06,
12/11/05, 10/6/05, 7/12/05, 5/23/05, 10/5/04, 5/13/04, 2/26/04, 2/11/04,
10/20/03, 9/28/03, 5/23/03, 3/23/03, 2/14/03, 1/27/03, 9/18/02, 7/17/02,
5/6/02, |
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FOREWORD--This web site concerns: o Latent variable interactions and quadratics in theoretical (hypothesis
testing) models involving survey data,
ando Testing these models. Its contents are intended for Ph.D. students, and theoretical and applied researchers, who are familiar with latent variables and structural equation analysis software such as LISREL, EQS, AMOS, etc., but are just getting started with latent variable interactions and quadratics. Interactions are not only "fashionable" lately, experience suggests they tend to obscure model test results (significances) when they are not specified in the model (but, please see "ALSO, just a reminder..." in the INTRODUCTION section below for more). NEWS: Comments on using PLS in theory tests involving survey data are available.
(Please see "Why are reviewers complaining about the use of PLS in my paper?
in the Questions of the Moment section below.) A suggested approach for remedying a "not Positive Definite" message ("Ill
Conditioned" in exploratory factor analysis) in theoretical model (hypothesis) tests
with survey data and structural equation analysis is available (please see "How does
one remedy a "not Positive Definite" message?" in the Questions of the Moment
section below).
The paper on improving AVE has been revised, with some surprising results (e.g.,
most of the "discriminant validity" tests are not trustworthy in survey-data theory
tests with real-world data).A suggested approach for testing (truly) categorical variables in theoretical model (hypothesis) tests with structural equation analysis is available (please see "How does one estimate categorical variables in theoretical model tests using structural equation analysis?" in the Questions of the Moment section below). Specifications for interactions forms besides XZ are available by e-mail. This may not sound like much, but XZ is not the only form an interaction can take. (E.g., X/Z and XZ2 are also interactions, and experience suggests they behave like XZ.) So, testing an hypothesized moderation with just XZ is not sufficient to test the moderation hypothesis 1) "Z moderates the X-Y association." Specifically, if XZ turns out to be nonsignificant, this does not disconfirm hypothesis 1) above (i.e., there may still be an interaction, its just not of the form "X times Z"). Experience suggests that X/Z, XZ2 or another interaction form may be significant when the XZ-Y association is nonsignificant, and there is strong theoretical support for Z moderating the X-Y association. Comments on using regression to test an hypothesized interaction are available. (Please see "Why are reviewers complaining about the use of moderated multiple regression in my paper? in the Questions of the Moment section below.) The suggestions below for estimating an endogenous interaction have changed.
The EXCEL template for estimating an indirect interaction is available--(please see
"Please Note: If you are estimating an interaction involving an endogenous variable..."
in the INTRODUCTION section below).
A paper on hypothesizing interactions is available (how interactions might be
"theorized"--what evidence suggests there might be an interaction in a model, how an
hypothesized interaction might be theoretically justified (argued for), etc.). (Please
see "Interactions May Be the Rule Rather than the Exception, But..." in the SELECTED
PAPERS ON LATENT VARIABLE INTERACTIONS AND QUADRATICS section below.)
Coming Attractions:
o A paper on estimating mixed (SEM) models with Formative and Reflective LV's. LV's
with poor psychometric properties (e.g., low AVE) also might be estimated as
Formative (with supporting arguments).
o An EXCEL template to help provide a detailed interpretation of a significant
Interaction or Quadratic (please. e-mail me for a draft template).Recent Additions and Changes in this Web Page (indicated by "New," "Revised" or
"Updated" below):
o Suggested remedies for low Average Variance Extracted are provided,
o The "Why is my hypothesized interaction or quadratic nonsignificant?" paper
(below) is being revised to account for the interaction forms besides XZ,
o A paper on the using of regression to test an hypothesized interaction that links
to a paper titled "What is Structural Equation Analysis?"
o The cubics paper is revised, and an EXCEL template for specifying cubics is
provided,
o FAQ's A, B and C address all the interaction/quadratic estimation techniques, and
o Several EXCEL templates calculate reliability and Average Variance Extracted for
XZ, XX and ZZ. (The quadratic XX, for example, could be viewed as the
interaction of X with itself.).
Please note: If you have visited this web site before, and the latest "Updated" date
(above) seems old, or, if you are actively estimating an interaction or quadratic,
you may want to click on your browser's "Refresh" or "Reload" button on the browser
toolbar (above) to view the current version of this web page. | ||||||||||
All the material on this web site is copyrighted, but you may save it and print it out. My only request is that you please cite any material that is helpful to you, either as a "book" (the APA citation for this website "book" is Ping, R.A. (2001). "Latent Variable Research." [on-line paper]. http://home.att.net/~rpingjr/ research1.htm.), or using the individual citations for each of the papers, EXCEL templates, monographs, etc. shown below. Don't forget to Refresh: Many of the links on this web site are in Microsoft WORD.
If you have viewed one or more of them before, the procedure to view the latest
(refreshed) version of them is tedious ("Refresh" does not work for Word documents
on the web). With my apologies for the tediousness, to refresh any (and all) Word
documents, please click on "Tools" on the browser toolbar (above), then click on
"Internet Options...." Next, in the "General" tab, find the "Temporary Internet Files"
section and click on "Delete Files...." Then, click in the "Delete all offline content" box,
and click "OK." After that, close this browser window, then re-launch it so the latest
versions of all the WORD documents are forced to download.Your questions are encouraged; just send an e-mail to rping@wright.edu. Don't worry about being an expert in latent variables, structural equation modeling (SEM) or structural equation analysis, or using "correct" terminology or perfect English. A Table of Contents or Index to this website is not available. Please consider using your browser's search capability to go to the relevant material. For example, to find the EXCEL templates click on "Edit" on the browser toolbar (above), and type the word "EXCEL" in the "Find what:", then click on "Find...". | ||||||||||
INTRODUCTION |
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| (N e w) |
Please Note: If you are estimating an interaction
involving one or more endogenous variables please click here--things
are different in this case.
ALSO, please remember that interactions and quadratics should be hypothesized before the model is ever tested with data. Please be aware that the only situations where one can search for significant interactions or quadratics is 1) when one wishes to explain a non-significant (NS) first-order model association (e.g., is there an interaction, XZ, or quadratic, ZZ, masking the hypothesized Z-->Y association?), or 2) where one wishes to investigate a significant association(s) to see if it is conditional (i.e., moderated), as routinely done in ANOVA studies (e.g., an association that was NS or of a different sign in a previous study), and thus improve interpretation of the model estimation results. In the first case, any significant "suppressor" interaction XZ or quadratic ZZ could be offered as a possible explanation for the NS Z-Y association in the Discussion section of the paper. In the second case, any significant conditional (moderated) association could be the basis for noting that the hypothesized Z-->Y association actually depended on the levels of X in the study for its strength and significance (see "Interpreting Latent Variable Interactions" in the SELECTED PAPERS...section below). Any moderated Z-->Y association(s) discovered after the fact also could be hypothesized in the Discussion section, then tested in a follow-up study, or replication, to investigate whether or not it simply was significant by chance in the present study (see "Hypothesized Associations and Unmodeled Latent Variable Interactions/Quadratics: An F-Test..." in the SELECTED PAPERS...section below for more). In absence of motivation 1 or 2 above, hunting for significant interactions or quadratics, not hypothesized before the model was tested (i.e., to "improve" a paper's contribution), is considered "poor science." It can tempt one to add an interaction or quadratic hypothesis as though it were hypothesized before the data was collected. And, it changes one's "hypotheses-before-first-test" model-testing ("confirmatory") study into a "test-before-hypothesis" model-building (exploratory) study. This in turn increases the likelihood that significant associations in the model exist only by chance (they are spuriously significant, and they exist in the present sample only). | |||||||||
| Questions of the Moment | ||||||||||
| "What about the alternative specifications for a Latent Variable (LV) interaction?" | ||||||||||
| An informal review in 2005 of substantive Social Science journal articles written since Kenny and Judd's (1984) seminal proposal for specifying LV interactions and quadratics found that the most frequently encountered specifications for LV interactions in substantive articles were: Jaccard and Wan (1995) (which specifies a 4-product-indicator subset1 of the Kenny and Judd interaction (product) indicators to avoid the model fit problems that occur when all of the Kenny and Judd indicators are specified--46 citations); Mathieu, Tannenbaum and Salas (1992) (which has not been formally evaluated for possible bias and inefficiency (see Cortina, Chen and Dunlap 2001 for other difficulties)--51 citations); and Ping (1995) (41 citations). (See FAQ's A, B and C in the Frequently Asked Questions section below for more.) | ||||||||||
| (N e w) |
"Is there an example that shows all the steps
involved in estimating a latent variable
interaction/quadratic?" |
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| (N e w) |
"How does one estimate categorical variables in theoretical model tests using structural equation analysis?" | |||||||||
| The
short
answer is, with considerable effort. In the popular structural equation analysis
software (e.g., LISREL, EQS, Amos, etc.), the term "categorical
variable" usually is used to mean an ordinal variable (e.g., an
attitude measured by Likert scales), rather than a nominal or "truly
categorical" variable (e.g., Marital Status, with the categories
Single, Married, Divorced, etc.), and typically there is no provision for
"truly" categorical variables. In regression, (truly)
categorical variables are estimated using "dummy" variables, and
a similar approach might be used in structural equation
analysis models with latent variables and a truly
categorical variable.
However, there are several issues in this mixed model. (Please click here for a paper on this subject, then please e-mail me--I have more suggestions.) |
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| (N e w) |
"Why
are reviewers complaining about the use of moderated multiple regression
in my paper?" (Please click here for a paper on this matter.) |
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| (N e w) |
"How should PRELIS or similar "preprocessor"
software be used with LISREL, EQS, AMOS, etc. to
create interactions/quadratics?" |
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| (N e w) |
"Why should applied researchers be interested in interactions/quadratics?" | |||||||||
|
Contrary to
conventional practice, interactions and quadratics
also may be important in applied research (model
building in econometrics, epidemiology, market response models,
biostatistics, etc.). Not to explain additional variance in a target variable, but to
better understand, explain and predict important relationships in a model.
Anecdotally, it is
not widely known in applied research that
important model effects may not be "Imperative"
(e.g., the latent variable Y increases/decreases with X). Instead, these
effect may be "Conditional" (e.g., Y
increases with X when Z is at a high level (strong), but Y is unrelated to
X, or it decreases with X, when Z is at a lower level (weaker)). (Please click here for a paper on this matter.) |
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| (N e w) |
"Is there any way to improve Reliability or Average Variance Extracted (AVE) in an interaction?" | |||||||||
| Please see the comments below in, "Is there any way to improve Average Variance Extracted (AVE) in a Latent Variable X?" (Interaction/quadratic reliability and AVE are improved by improving reliability and AVE in X and Z.) | ||||||||||
| (N e w) |
"When theory proposes an X-Y association and it also proposes that Z moderates this association, but theory is mute about or doesn't propose a Z-Y association, why does one still include Z in addition to X and XZ in the model to be tested?" | |||||||||
| In short, excluding the Z-Y (and/or the X-Y) association when XZ-Y
is hypothesized to be significant, can bias all structural coefficients
and standard errors in the proposed model. This in turn casts a shadow on
the trustworthiness of the test of the proposed model. In addition, and
perhaps surprisingly, if XZ is significant, excluding Z from the model
biases the (significant) factored ("true" contingent)
association of Z with Y, EVEN WHEN THE Z-Y ASSOCIATION IS HYPOTHESIZED TO
NOT EXIST IN THE POPULATION. (Please click here for more on this subject.) |
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| (N e w) |
"How is a cubic latent variable (LV) estimated?" |
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| Please see the paper on estimating a LV cubic in the "Selected Papers on Latent Variable Interactions and Quadratics" section (below). The "EXCEL templates..." section (below) includes a template to assist in calculating loadings, error variances, etc. for LV cubics. | ||||||||||
| "Why is my hypothesized
interaction or
quadratic nonsignificant?" (Please click here for a paper on this topic that is being revised--please e-mail me with any questions you may have on this topic.) |
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|
"Is there any way to
improve Average Variance Extracted (AVE) in a Latent
Variable X?" |
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"Is there any way to
speed up "item weeding" to find a set of items in a
multi-item measure that fits
the data?" |
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| "How might a 'mixed
interaction' XZ, where X is a manifest/observed/continuous/single-indicator, etc. variable (not a latent variable), be estimated?" (Please click here for a paper on this topic.) |
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| (Re- vis- ed) |
"Why is my hypothesized
interaction significant using a 'median split' of the data, or a
'2-group analysis,'
but not significant when specified in my model?" (Please click here for a paper on this subject.) |
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| (Re- vis- ed) |
"Why are most (or all)
of my hypothesized interactions not significant?" (Please click here for a paper on this matter.) |
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| "What is the Average
Variance Extracted (AVE) for a Latent Variable Interaction
(or Quadratic)?" (Please click here for a paper on this topic, then please e-mail me--I have more suggestions.) |
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| "What is the 'validity'
of a Latent Variable Interaction (or Quadratic)?" (Please click here for a paper on this subject.) |
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| (N e w) |
"How
does one remedy a "not Positive Definite" message?" (Please click here for a paper on this matter.) |
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| (N e w) |
"Why
are reviewers complaining about the use of PLS
in my paper?" (Please click here for a paper on this topic.) |
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| ______________ 1 Unfortunately, in theoretical model tests, deleting ("weeding" out) all but 4 of the Kenny and Judd product indicators to attain model-to-data fit raises several issues, including the reliability and validity of the resulting 4-item interaction or quadratic. Reliability is necessary for validity, and the reliability of an interaction specified with nearly all of its indicators deleted is unknown. (The formula for the reliability of XZ assumes XZ is operationally (unweeded) X times (unweeded) Z.) The face- or content-validity of a 4-item interaction or quadratic also is questionable (e.g., if nearly all the indicators of X and Z are unrepresented in the itemization XZ, for example, is XZ still the latent variables X and Z"?). Further, it is easy to show that in real-world data a weeded XZ's structural coefficient varies with the set of four indicators that are selected as its indicators. Unfortunately, the "best" four weeded indicators are unknown. Finally, an interaction with weeded Kenny and Judd product indicators cannot be "factored," which produces detailed interpretation problems because XZ is no longer (unweeded) X times (unweeded) Z. | ||||||||||
| Frequently Asked Questions | ||||||||||
(CLICK ON A RED DOT) (Re- vised) |
about Latent Variable Interactions and Quadratics in survey data E.g., The answer to FAQ D, "How does one test hypothesized interactions or quadratics?" may be a useful "cookbook" for Ph.D. students, and theoretical researchers interested in estimating their first Latent Variable Interaction or Quadratic in a theoretical model test using survey data. FAQ D also may be of interest to applied researchers interested in specifying a Latent Variable Interaction or Quadratic in a model. | |||||||||
| EXCEL TEMPLATES | ||||||||||
EXCEL Templates for expediting the specification of Latent Variable (LV) Interactions, Quadratics and cubics; for "weeding" measures to attain model fit; for Latent Variable Regression, etc. | ||||||||||
(CLICK ON A RED DOT) (Re- vised) |
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| BIBLIOGRAPHY | ||||||||||
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ON-LINE MONOGRAPHS | ||||||||||
(CLICK ON A RED DOT) |
LATENT VARIABLE INTERACTIONS AND QUADRATICS IN SURVEY DATA: A SOURCE BOOK FOR THEORETICAL MODEL TESTING (2nd Edition) About Latent Variable Interactions and Quadratics, and their estimation, with examples. Potentially of interest to Ph.D. students and researchers who conduct or teach theoretical model (hypothesis) testing using survey data. Includes a "fast start" section on estimating a latent variable interaction, a section on estimating multiple interactions and quadratics, how to interpret a significant interaction or quadratic, and pedagogical examples (232 pp.). The APA citation for this on-line monograph is Ping, R.A. (2003). Latent variable interactions and quadratics in survey data: a source book for theoretical model testing, 2nd edition. [on-line monograph]. http://home.att.net/~rpingjr/intquad2/ toc2.htm. | |||||||||
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TESTING LATENT VARIABLE MODELS WITH SURVEY DATA (2nd Edition) About
the results of a large study of theoretical model (hypothesis) testing
practices using survey data, with critical analyses, suggestions and
examples. Potentially of interest to Ph.D. students and researchers who
conduct or teach theoretical model testing using survey data. Contents
include the six steps in theoretical model (hypothesis) testing using
survey data; scenario analysis; alternatives to dropping items to attain
model-to-data fit; inadmissible solutions with remedies; interactions and
quadratics; and pedagogical examples (177 pp.). The APA citation for this on-line monograph is Ping, R.A. (2004). Testing latent variable models with survey data, 2nd edition. [on-line monograph]. http://home.att.net/~rpingjr/lv1/toc1.htm . | ||||||||||
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SELECTED PAPERS ON LATENT VARIABLE INTERACTIONS AND QUADRATICS | ||||||||||
(CLICK ON A RED DOT) |
"Interactions May Be the Rule Rather than the Exception, But...: A Note on Issues in Estimating Interactions in Theoretical Model Tests" (An earlier version of Ping 2008, Am. Mktng. Assoc. (Summer) Educators’ Conf. Proc.). The paper critically addresses theory-testing questions on conceptualizing, estimating and interpreting interactions in survey data. For example, what evidence suggests that an interaction should be hypothesized? Is an interaction a construct or a mathematical form, or both? Is specifying the interaction between X and Z, for example, as XZ a sufficient disconfirmation test? (Pls. be patient, the download time may be a bit long). | |||||||||
"On the Maximum of About Six Indicators per Latent Variable with Real-World Data." (An earlier version of Ping 2008, Am. Mktng. Assoc. (Winter) Educators’ Conf. Proc.). The paper suggests an explanation and remedies for the puzzling result that Latent Variables in theoretical model testing articles have a maximum of about 6 indicators. (Pls. be patient, the download time may be a bit long). | ||||||||||
"Second-Order Latent Variable Interactions, and Second-Order Latent Variables." (An earlier version of Ping 2007, Am. Mktng. Assoc. (Winter) Educators’ Conf. Proc.). The paper proposes several specifications for a Second-Order Latent Variable interaction. (Pls. be patient, the download time may be a bit long). | ||||||||||
"Notes on Estimating Cubics and other 'Powered' Latent Variables." (An earlier version of Ping 2007, Am. Mktng. Assoc. (Summer) Educators’ Conf. Proc.). The paper discusses "satiation" and "diminishing returns," infrequently explored topics in theoretical model tests, and a Latent Variable (LV) that is related to a quadratic, a cubic. The paper suggests a specification for this difficult-to-specify LV. (Pls. be patient, the download time may be a bit long). | ||||||||||
"Estimating Latent Variable Interactions and Quadratics: Examples,
Suggestions and Needed Research" (An earlier version of Ping 1998, in
Interaction..., revised December 2006).
The paper provides estimation examples, including LISREL and EQS code. The revision
also corrects several errors.
(Pls. be patient, the download time may be a bit long). | ||||||||||
"Pseudo Latent Variable Regression: an Accessible Estimation Technique for Latent Variable Interactions," (An earlier version of Ping 2003, 2003 Acad. of Mktng. Sci. Conf. Proc., Miami: Acad. of Mktng Sci., revised October, 2003). The paper proposes a reliability-based OLS Regression estimator for Latent Variable
Interactions and Quadratics.
(Pls. be patient, the download time may be a bit long). | ||||||||||
"Improving the Detection of Interactions in Selling and Sales Management Research" (An earlier version of Ping 1996, J. of Personal Selling and Sales Mgt., revised October 2003). Using Monte Carlo simulations, the paper evaluates non-structural equation analysis approaches to detecting a Latent Variable Interaction such as median splits. (Pls. be patient, the download time may be a bit long). | ||||||||||
"Interpreting Latent Variable Interactions" (An earlier version of Ping 2002, Am. Mktng. Assoc. (Winter) Educators’ Conf. Proc., revised June 2002). The paper suggests an approach to developing detailed interpretation of a significant Latent Variable Interaction or Quadratic, that reveals the subset(s) of the domain of a moderated variable where it is significant and non significant. (Pls. be patient, the download time may be a little long). | ||||||||||
"A Parsimonious Estimating Technique for Interaction and Quadratic Latent Variables" (An earlier version of Ping 1995, JMR, revised July 2001). The paper proposes a single indicator specification for Latent Variable Interactions and Quadratics that addresses the model-to-data fit problem associated with specifying these variables in real-world data without omitting interaction items and thus impairing reliability and validity; the proposed specification can be used with LISREL, EQS, AMOS, CALIS, etc. (Pls. be patient, the download time may be a little long). | ||||||||||
"Latent Variable Interaction and Quadratic Effect Estimation: A Two-step Technique Using Structural Equation Analysis" (An earlier version of Ping 1996, Psych. Bull., revised July 2001). The paper proposes a "2-step" Kenny and Judd (1984) estimation approach for Latent Variable Interactions and Quadratics with LISREL, EQS, AMOS, CALIS, etc. This approach is useful with a consistent subset of product indicators (see Chapter VIII.--SxA Unidimensionalization, in the monograph, LATENT VARIABLE INTERACTIONS... above), and other subset itemizations, with software that does not permit direct estimation (e.g., EQS, AMOS, etc.). (Pls. be patient, the download time may be a bit long). | ||||||||||
"Latent Variable Regression: A Technique for Estimating Interaction and Quadratic Coefficients" (An earlier version of Ping 1996, Multiv. Behav. Res., revised July 2001). The paper proposes a measurement-error-adjusted regression technique for Latent Variables, including Interactions and Quadratics (the Standard Error is explained in the paper below, "A Suggested Standard Error..."). This approach is useful in situations where regression is valuable. These situations include (applied) model building (e.g., in market research, econometrics, epidemiology, biostatistics, etc.) where many candidate models are estimated using easily implemented "stepwise" and "backward elimination" procedures to determine the model that "best fits" the calibration data; and, theoretical model (hypothesis) testing of a model that combines nominal (categorical) variables with ordinal or continuous latent variables. (Pls. be patient, the download time may be a little long). | ||||||||||
"A Suggested Standard Error for Interaction Coefficients in Latent Variable Regression" (An earlier version of Ping 2001, Acad. Mktng. Sci. Proc., revised September 2001). The paper suggests a Standard Error term for Latent Variable Regression (see above). (Pls. be patient, the download time may be a bit long). | ||||||||||
| WORKING PAPERS MENTIONED ELSEWHERE ON THE WEB SITE | ||||||||||
(CLICK ON THE RED DOT) |
"Hypothesized Associations and Unmodeled Latent Variable Interactions/ Quadratics: An F-Test, Lubinski and Humphreys Sets, and Shortcuts Using Reliability Loadings." The paper proposes an approach to post-hoc probing for Latent Variable Interactions and Quadratics in order to explain a non significant hypothesized association. (Pls. be patient, the download time may be a little long.) The APA citation for this on-line paper is Ping, R.A. (2006). "Hypothesized Associations and Unmodeled Latent Variable Interactions/Quadratics: An F-Test, Lubinski and Humphreys Sets, and Shortcuts Using Reliability Loadings." [on-line paper]. http://home.att.net/~rpingjr/Ftest10.doc . | |||||||||
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