Biomedical subjects

F A Gruber

Publications and source records attributed to F A Gruber.

5 recordsLinked to original sources

PubMed1999

Tutorial: survival analysis--a statistic for clinical, efficacy, and theoretical applications.

Current demands for increased research attention to therapeutic efficacy, efficiency, and also for improved developmental models call for analysis of longitudinal outcome data. Statistical treatment of longitudinal speech and language data is difficult, but there is a family of statistical techniques in common use in medicine, actuarial science, manufacturing, and sociology that has not been used in speech or language research. Survival analysis is introduced as a method that avoids many of the statistical problems of other techniques because it treats time as the outcome. In survival analysis, probabilities are calculated not just for groups but also for individuals in a group. This is a major advantage for clinical work. This paper provides a basic introduction to nonparametric and semiparametric survival analysis using speech outcomes as examples. A brief discussion of potential conflicts between actuarial analysis and clinical intuition is also provided.

Child↗

PubMed1999

Probability estimates and paths to consonant normalization in children with speech delay.

Probable ages of normalization were calculated for 24 children with speech delay, using Kaplan-Meier analysis and a threshold score of 85% on the Percent of Consonants Correct, Percent of Consonants Correct-Adjusted, and Percent of Consonants Correct-Revised metrics. Simple formulas are provided that permit calculation of the likelihood that individual children with speech delay will normalize by a given age. The sex of a child was found to have no significant influence on age of normalization. Analysis revealed two different paths to normalization. In Path A, errors of deletion, substitution, and omission declined as correct productions increased. In Path B, common clinical distortions increased as deletions and substitutions decreased. The ages of more and less rapid phonological gain correspond to and partially explain the findings of Shriberg, Gruber, and Kwiatkowski (1994), who studied more severely involved children. Children who follow Path B are those who retain residual errors in their speech.

Child, Preschool↗

PubMed1999

Variability and sequential order of consonant normalization in children with speech delay.

A source of discrepancy among attempts to establish a rank order in the development of English consonants has been the inability to cope concurrently with principled generalization and individual variability. This problem may be surmounted by survival analytic techniques. From the conversational speech of 24 children with speech delay (SD) recorded over 2 years, a Kaplan-Meier (KM) survival analysis provided a rank order of acquisition for all probabilities above .75. The rank ordering by chronological age uncovered an alignment by place and manner of articulation comparable to, but not identical with, the predictions of Jakobson (1941, 1968). When the derived normalization probabilities for the speech delayed children were lagged according to the strong delay hypothesis (Shriberg, Gruber, & Kwiatkowski, 1994), they were shown to converge with previous normative studies and the age of speech-sound determinations (Prather, Hedrick, & Kern, 1975; Sander, 1972). The convergence of results is interpreted both as an argument for generalizability and as support for the strong delay hypothesis.

Age Factors↗

PubMed1994

Developmental phonological disorders. II. Short-term speech-sound normalization.

A companion paper (Shriberg & Kwiatkowski, 1994) provides a descriptive profile of three samples of children (n = 178) with developmental phonological disorders. The present paper describes a conceptual framework for short-term and long-term speech-sound normalization research and reports 1-year normalization outcomes for 54 of the children described in the companion paper. Although certain individual speech variables were significantly associated with normalization, there were no speech, prosody-voice, or risk-factor variables that discriminated children who achieved short-term speech-sound normalization in 1 year. Findings are discussed in relation to a two-factor framework to study and predict speech-sound normalization in developmental phonological disorders (Kwiatkowski & Shriberg, 1993; Shriberg, Kwiatkowski, & Gruber, 1992).

Bias↗

PubMed1994

Developmental phonological disorders. III: Long-term speech-sound normalization.

Prior articles in this series provide a descriptive profile of 178 children with developmental phonological disorders (Shriberg & Kwiatkowski, 1994) and predictive correlates of short-term speech-sound normalization in 54 children (Shriberg, Kwiatkowski, & Gruber, 1994). The present article reports findings from a study of 10 children with developmental phonological disorders whose progress was followed at least once yearly for 7 years. Analyses characterize the sequence, rates, and error patterns of long-term speech-sound normalization in relation to developmental perspectives on the nature of children's phonological disorders. Findings are interpreted to support the hypothesis of a critical period for speech-sound development, with long-term normalization of significant speech delay reaching a chronological age boundary at approximately 8.5 years.

Age Factors↗