Riable in this analysis. Frequency of stuttered disfluencies was the independent variable. The sample for this analysis included the same 472 children reported above. Parents of 254 children expressed concerns about their child’s stuttering (184 boys, 70 girls, M(age) =6ROC curve plots the sensitivity of the model against (1 ?the specificity) of the model for different threshold of the predicted probability. Sensitivity is defined as the percent of cases correctly identified to have a condition/disease, and specificity ?as the percent of cases correctly identified to be “condition-free”/healthy. J Commun Disord. Author manuscript; available in PMC 2015 May 01.Tumanova et al.Pagemonths), and parents of 218 children expressed no concerns about stuttering (105 boys, 113 girls, M(age) = 50 months). Children whose caregivers expressed concerns about stuttering exhibited an average of 8.11 of stuttered (range: .33?3.67 ) and 3.74 of non-stuttered disfluencies (range: 0?2.33 ) in their conversational speech. Children whose caregivers did not order Pepstatin express concern about stuttering exhibited an average of 1.52 (range: 0?0.67 ) of stuttered and 3.15 (range: 0?1 ) of non-stuttered disfluencies in their speech. Logistic purchase ML390 regression model fitted to the data indicated that the number of stuttered disfluencies is a significant predictor of parental concern about stuttering (Wald 2 = 94.45, df = 1, p < .0001; = .262), with 90.8 of children whose parents are not concerned about stuttering and 82.3 of children whose parents are concerned correctly classified based on the frequency of stuttered disfluencies. The classification table is presented in Table 8. Using parental concern as a means for talker-group classification, the present authors sought to determine the sensitivity and specificity of the 3 stuttered disfluencies criterion (e.g., Conture, 2001; Yairi Ambrose, 2005). In other words, is the 3 criterion a reasonable means for talker-group classification when parental concern is the "gold standard?" The area under the ROC curve, a measure of strength of predictive capacity of the model over all cut points, for stuttered disfluencies was .91. This indicated that the model has good discriminatory ability. Using 3 stuttered disfluencies as a cut-off score for talker-group classification resulted in sensitivity of .80 (true positive classifications) and specificity of .92 (yielding false positive classifications on the order of .08), suggesting that the 3 criterion has a strong and clinically meaningful association with parental concern. The sensitivity?specificity analysis for stuttered disfluencies is presented in Table 9.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript4. DiscussionThe present study resulted in four main findings: first, frequency distributions of three common disfluency types (stuttered, non-stuttered and total disfluencies) were non-normal. They followed a negative binomial distribution, a Poisson-like count with larger dispersion than true Poisson. Second, there was a significant difference between preschool-age CWS and CWNS in frequency of stuttered as well as non-stuttered disfluencies. Furthermore, the number of non-stuttered and total disfluencies were significant predictors for talker group classification. Third, for both talker groups, expressive vocabulary (as measured by the EVT) and age were associated with the frequency of non-stuttered disfluencies. Moreover, gender was associated with t.Riable in this analysis. Frequency of stuttered disfluencies was the independent variable. The sample for this analysis included the same 472 children reported above. Parents of 254 children expressed concerns about their child's stuttering (184 boys, 70 girls, M(age) =6ROC curve plots the sensitivity of the model against (1 ?the specificity) of the model for different threshold of the predicted probability. Sensitivity is defined as the percent of cases correctly identified to have a condition/disease, and specificity ?as the percent of cases correctly identified to be "condition-free"/healthy. J Commun Disord. Author manuscript; available in PMC 2015 May 01.Tumanova et al.Pagemonths), and parents of 218 children expressed no concerns about stuttering (105 boys, 113 girls, M(age) = 50 months). Children whose caregivers expressed concerns about stuttering exhibited an average of 8.11 of stuttered (range: .33?3.67 ) and 3.74 of non-stuttered disfluencies (range: 0?2.33 ) in their conversational speech. Children whose caregivers did not express concern about stuttering exhibited an average of 1.52 (range: 0?0.67 ) of stuttered and 3.15 (range: 0?1 ) of non-stuttered disfluencies in their speech. Logistic regression model fitted to the data indicated that the number of stuttered disfluencies is a significant predictor of parental concern about stuttering (Wald 2 = 94.45, df = 1, p < .0001; = .262), with 90.8 of children whose parents are not concerned about stuttering and 82.3 of children whose parents are concerned correctly classified based on the frequency of stuttered disfluencies. The classification table is presented in Table 8. Using parental concern as a means for talker-group classification, the present authors sought to determine the sensitivity and specificity of the 3 stuttered disfluencies criterion (e.g., Conture, 2001; Yairi Ambrose, 2005). In other words, is the 3 criterion a reasonable means for talker-group classification when parental concern is the "gold standard?" The area under the ROC curve, a measure of strength of predictive capacity of the model over all cut points, for stuttered disfluencies was .91. This indicated that the model has good discriminatory ability. Using 3 stuttered disfluencies as a cut-off score for talker-group classification resulted in sensitivity of .80 (true positive classifications) and specificity of .92 (yielding false positive classifications on the order of .08), suggesting that the 3 criterion has a strong and clinically meaningful association with parental concern. The sensitivity?specificity analysis for stuttered disfluencies is presented in Table 9.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript4. DiscussionThe present study resulted in four main findings: first, frequency distributions of three common disfluency types (stuttered, non-stuttered and total disfluencies) were non-normal. They followed a negative binomial distribution, a Poisson-like count with larger dispersion than true Poisson. Second, there was a significant difference between preschool-age CWS and CWNS in frequency of stuttered as well as non-stuttered disfluencies. Furthermore, the number of non-stuttered and total disfluencies were significant predictors for talker group classification. Third, for both talker groups, expressive vocabulary (as measured by the EVT) and age were associated with the frequency of non-stuttered disfluencies. Moreover, gender was associated with t.
