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  • 1
    Electronic Resource
    Electronic Resource
    Modern Insights About Pearson’s Correlation and Least Squares Regression (2001)
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    International journal of selection and assessment 9 (2001), S. 0 
    Details
    ISSN: 1468-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: As is well known, Pearson’s correlation, ρ, can be used to characterize how well a least squares regression line fits data, and it provides a test of the hypothesis that two measures are independent. However, many articles in statistical journals indicate that the usual estimate of ρ, r, is sensitive to at least six features of data, and that least squares regression and ρ are not robust in the sense reviewed in this article. In practical terms, r can be a highly unsatisfactory measure of the strength of an association, no matter how large the sample size might be. One specific problem is that it can miss strong associations that are detected by more modern techniques. The practical problems with r reflect fundamental concerns about a strict reliance on least squares regression. A few of the many modern methods for dealing with these concerns are briefly indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1468-2389.00172
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A generally robust approach to hypothesis testing in independent and correlated groups designs (2003)
    Oxford, UK : Blackwell Publishing
    Psychophysiology 40 (2003), S. 0 
    Details
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Standard least squares analysis of variance methods suffer from poor power under arbitrarily small departures from normality and fail to control the probability of a Type I error when standard assumptions are violated. These problems are vastly reduced when using a robust measure of location; incorporating bootstrap methods can result in additional benefits. This paper illustrates the use of trimmed means with an approximate degrees of freedom heteroskedastic statistic for independent and correlated groups designs in order to achieve robustness to the biasing effects of nonnormality and variance heterogeneity. As well, we indicate when a boostrap methodology can be effectively employed to provide improved Type I error control. We also illustrate, with examples from the psychophysiological literature, the use of a new computer program to obtain numerical results for these solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1469-8986.00060
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    Paper (German National Licenses)
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  • 3
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    A Note on Measuring Item Bias (1984)
    Washington D.C., Wash. : Periodicals Archive Online (PAO)
    The Journal of Experimental Education. 53:2 (1984/1985:Winter) 114 
    Details
    ISSN: 0022-0973
    Topics: Education
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:h101-1984-053-02-000008
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    Paper (German National Licenses)
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  • 4
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    A Closed Sequential Procedure for Answer-Until-Correct Tests (1982)
    Washington D.C., Wash. : Periodicals Archive Online (PAO)
    The Journal of Experimental Education. 50:4 (1982:Summer) 219 
    Details
    ISSN: 0022-0973
    Topics: Education
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:h101-1982-050-04-000009
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    Paper (German National Licenses)
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  • 5
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    A Simple Model for Diagnostic Testing When There Are Several Types of Misinformation (1983)
    Washington D.C., Wash. : Periodicals Archive Online (PAO)
    The Journal of Experimental Education. 52:1 (1983:Fall) 57 
    Details
    ISSN: 0022-0973
    Topics: Education
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:h101-1983-052-01-000008
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  • 6
    Electronic Resource
    Electronic Resource
    An algorithm for comparing medians (1989)
    Springer
    Psychometrika 54 (1989), S. 345-348 
    Details
    ISSN: 1860-0980
    Keywords: variance of the sample median
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract An algorithm is presented for computing a test statistic for comparing medians based on a small-sample size estimate of the variance of the usual sample median.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02294526
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Comparing one-step m-estimators of location corresponding to two independent groups (1992)
    Springer
    Psychometrika 57 (1992), S. 141-154 
    Details
    ISSN: 1860-0980
    Keywords: Huber's Ω function ; L-statistics ; trimming ; medians ; bootstrap ; Mann-Whitney test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract Experience with real data indicates that psychometric measures often have heavy-tailed distributions. This is known to be a serious problem when comparing the means of two independent groups because heavy-tailed distributions can have a serious effect on power. Another problem that is common in some areas is outliers. This paper suggests an approach to these problems based on the one-step M-estimator of location. Simulations indicate that the new procedure provides very good control over the probability of a Type I error even when distributions are skewed, have different shapes, and the variances are unequal. Moreover, the new procedure has considerably more power than Welch's method when distributions have heavy tails, and it compares well to Yuen's method for comparing trimmed means. Wilcox's median procedure has about the same power as the proposed procedure, but Wilcox's method is based on a statistic that has a finite sample breakdown point of only 1/n, wheren is the sample size. Comments on other methods for comparing groups are also included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02294663
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    The percentage bend correlation coefficient (1994)
    Springer
    Psychometrika 59 (1994), S. 601-616 
    Details
    ISSN: 1860-0980
    Keywords: robust methods ; test of independence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract A well-known result is that the usual correlation coefficient,ρ, is highly nonrobust: very slight changes in only one of the marginal distributions can alterρ by a substantial amount. There are a variety of methods for correcting this problem. This paper identifies one particular method which is useful in psychometrics and provides a simple test for independence. It is not recommended that the new test replace the usual test ofH 0:ρ = 0, but the new test has important advantages over the usual test in terms of both Type I errors and power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02294395
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    A one-way random effects model for trimmed means (1994)
    Springer
    Psychometrika 59 (1994), S. 289-306 
    Details
    ISSN: 1860-0980
    Keywords: Winsorizing ; contamination ; resistance ; intraclass correlation ; Kruskal-Wallis ; Rust-Fligner method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract The random effects ANOVA model plays an important role in many psychological studies, but the usual model suffers from at least two serious problems. The first is that even under normality, violating the assumption of equal variances can have serious consequences in terms of Type I errors or significance levels, and it can affect power as well. The second and perhaps more serious concern is that even slight departures from normality can result in a substantial loss of power when testing hypotheses. Jeyaratnam and Othman (1985) proposed a method for handling unequal variances, under the assumption of normality, but no results were given on how their procedure performs when distributions are nonnormal. A secondary goal in this paper is to address this issue via simulations. As will be seen, problems arise with both Type I errors and power. Another secondary goal is to provide new simulation results on the Rust-Fligner modification of the Kruskal-Wallis test. The primary goal is to propose a generalization of the usual random effects model based on trimmed means. The resulting test of no differences among J randomly sampled groups has certain advantages in terms of Type I errors, and it can yield substantial gains in power when distributions have heavy tails and outliers. This last feature is very important in applied work because recent investigations indicate that heavy-tailed distributions are common. Included is a suggestion for a heteroscedastic Winsorized analog of the usual intraclass correlation coefficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02296126
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Comparing the variances of dependent groups (1989)
    Springer
    Psychometrika 54 (1989), S. 305-315 
    Details
    ISSN: 1860-0980
    Keywords: bootstrap ; median ; trimmed mean ; signed rank test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Psychology
    Notes: Abstract Recently several new attempts have been made to find a robust method for comparing the variances ofJ dependent random variables. However, empirical studies have shown that all of these procedures can give unsatisfactory results. This paper examines several new procedures that are derived heuristically. One of these procedures was found to perform better than all of the robust procedures studied here, and so it is recommended for general use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02294522
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    Paper (German National Licenses)
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