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1. Dyslexia Index (Dx) Factors by research subgroup


dyslexia indexThe data summary tables collected here show a breakdown analysis of the Dyslexia Index Factors for each research subgroup of interest in the project. This analysis was completed in SPSS with the Rotated Component Matrix available here which summarizes the resulting distribution into factors of the scale-item dimensions from the Dyslexia Index section of the main research QNR.

The Principal Factor Analysis is reported on the StudyBlog ('Principal Component Analysis') where this first Table 1 (below) is also presented. This table shows the factor-split Dx values for each respondent in the subgroup of particular interest, DNI. This is respondents with no reported dyslexia but who were sifted out from research group ND because their Dx values suggest that they are presenting dyslexia-like profiles. The boundary value used in the sifting process was Dx > 592.5. A report outlining the research decisions that arrived at this value is presented on the StudyBlog.

The other research subgroups contain more datasets (n=47, n=44) than subgroup DNI (n=18) and so where just the summary data is referred to in the blog-post ('Dyslexia Index factor profiles for respondents in the research subgroups'), the complete data tables are presented in full below. Research subgroup DI-600 is respondents with reported dyslexia whose Dyslexia Index takes a value of Dx > 592.5; research subgroup ND-400 is respondents with no reported dyslexia whose Dyslexia Index takes a value of Dx < 400

There is work to do in understanding these data breakdowns but a first inspection reveals some interesting features which are summarised in the blog-post.


A full discussion to attempt to understand the meaning of this data will be presented in the final thesis.

Respondents highlighted in green text.are linked to their additional written commentaries submitted in their completed QNR.

Table 1: Dyslexia Index Factors for research subgroup DNI

click to open the panelDyslexia Index Factors for research subgroup DNI - summary


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Dx overall Student respondents Dx Factor 1 Dx Factor 2 Dx Factor 3 Dx Factor 4 Dx Factor 5
  research group ND
subgroup DNI
Reading, Writing, Spelling Thinking & Processing Organization & Time Management Verbalizing & Scoping Working Memory
684.75 means 763.01 647.60 635.53 734.64 668.82
76.55 / 18.56 st dev / st err 141.87 / 34.41 123.49 / 29.95 152.28 / 36.93 257.97 / 62.57 668.82 / 61.58
648 < μ < 721 95% CI for μ 696 < μ < 830 589 < μ < 706 563 < μ 708 612 < μ < 857 548 < μ <790
            view this data as a chart: link to a chart
597.39 #75931558 916.77 432.65 489.60 634.84 609.76
604.94 #96408048 824.11 746.99 512.26 80.00 489.51
619.58 #61624105 505.49 549.41 706.84 812.97 1000.00
639.45 #16730769 583.02 714.22 483.05 1000.00 390.24
642.01 #20048355 567.20 718.86 568.08 852.27 500.00
642.02 #57371454 635.70 546.16 753.05 976.64 648.78
642.26 #97653577 694.09 559.57 712.99 816.33 472.93
654.84 #99268333 840.57 472.01 493.79 666.09 749.02
655.32 #63726872 570.07 771.58 500.00 466.41 800.00
656.90 #14557932 786.18 646.99 576.10 835.23 269.27
659.87 #78323952 700.81 621.80 518.70 938.91 316.10
682.51 #18801333 851.97 604.32 445.99 549.45 753.90
708.61 #21388930 878.05 613.15 755.14 336.95 1000.00
731.52 #87083069 895.96 647.76 851.19 1000.00 339.02
746.04 #10498881 903.14 527.08 705.65 933.44 1000.00
753.67 #68379308 819.43 788.45 611.81 549.53 884.63
779.07 #84526262 781.43 821.46 755.25 774.53 878.29
909.43 #28565915 980.17 874.41 1000.00 1000.00 937.32

Table 2: Dyslexia Index Factors for research subgroup DI-600

click to open the panelDyslexia Index Factors for research subgroup DI-600 - summary


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Dx overall Student respondent Dx Factor 1 Dx Factor 2 Dx Factor 3 Dx Factor 4 Dx Factor 5
  research group DI
subgroup DI-600
Reading, Writing, Spelling Thinking & Processing Organization & Time Management Verbalizing & Scoping Working Memory
717.32 means 794.50 700.42 615.72 772.72 589.20
69.92 / 10.26 st dev / st err 106.33 / 15.68 131.07 / 19.32 145.72 / 21.49 165.11 / 24.34 227.14 / 33.49
697 < μ <737 95% CI for μ 764 < μ < 825 663 < μ < 738 574 < μ < 658 725 < μ < 820 524 < μ < 655
            view this data as a chart: link to data chart
592.52 #32887925 756.18 332.24 458.14 794.45 725.61
595.04 #20726963 673.80 584.70 490.85 587.66 602.20
606.82 #10779962 618.41 455.34 461.30 763.28 509.76
616.91 #44789560 675.06 549.09 841.81 777.34 0.00
633.07 #61502858 674.11 554.91 515.25 944.53 573.17
634.44 #12595865 656.63 676.74 815.65 946.56 609.76
638.29 #95872552 500.00 500.00 500.00 500.00 500.00
641.94 #21789859 857.48 557.21 657.18 870.86 182.93
643.33 #44859855 790.31 634.68 506.78 691.09 0.00
653.86 #75137073 841.33 726.62 558.19 777.34 243.90
657.64 #50744483 816.86 692.21 464.18 786.25 628.78
665.17 #30598961 826.60 454.34 680.79 777.34 609.76
668.89 #69740230 685.51 703.20 829.94 500.00 665.85
669.98 #63170765 574.35 791.46 587.40 633.52 741.71
674.51 #67380181 699.88 598.26 730.96 899.92 981.71
679.93 #11098724 811.73 754.22 520.28 643.67 654.15
682.21 #67632469 795.15 689.66 763.39 919.84 70.00
690.70 #21694901 646.56 622.95 788.70 1000.00 882.93
698.65 #47581572 768.38 770.75 593.84 741.72 568.54
699.15 #74355805 935.42 796.00 473.90 679.38 531.71
702.32 #77173907 744.75 630.14 529.38 839.92 716.59
705.82 #41273845 835.32 655.16 744.63 1000.00 651.46
707.66 #21673654 875.96 808.45 462.60 632.11 573.90
716.10 #16359248 703.94 698.86 1000.00 459.92 140.24
719.63 #17465316 752.00 647.03 635.03 764.53 516.34
725.16 #78372084 756.29 797.72 312.43 644.53 609.76
728.64 #82550367 810.45 726.03 818.93 1000.00 869.51
735.19 #88952978 787.27 761.30 475.82 666.41 624.88
739.18 #56837694 839.45 778.70 588.64 510.00 556.83
745.66 #52594555 759.62 767.24 514.41 600.00 782.93
748.93 #90023507 809.69 729.06 468.64 772.11 662.20
751.23 #87564798 840.86 850.23 712.43 510.94 648.78
760.80 #38307943 974.01 616.62 760.40 911.25 637.07
763.09 #41496790 896.91 573.86 599.32 1000.00 609.76
768.97 #82055919 929.07 639.82 735.59 977.73 648.78
773.28 #22995924 784.61 871.28 474.86 973.28 644.88
778.04 #81973995 920.14 854.13 401.69 625.94 609.76
778.33 #49708220 844.13 772.37 696.21 549.69 585.37
778.46 #60363012 810.93 841.10 471.19 777.34 390.24
792.50 #87579284 909.41 715.75 488.14 888.67 875.12
796.62 #89059542 829.93 553.17 729.77 1000.00 1000.00
797.84 #74428045 811.09 903.93 567.34 568.59 747.80
797.98 #85897154 765.46 868.15 621.36 811.02 717.07
803.77 #77407616 975.06 817.24 667.80 777.34 420.73
807.36 #27618034 946.98 843.63 827.51 1000.00 604.39
835.65 #48997796 834.49 819.18 683.62 821.88 704.88
912.71 #69277072 989.74 934.93 713.73 1000.00 860.49

Table 3: Dyslexia Index Factors for research subgroup ND-400

click to open the panelDyslexia Index Factors for research subgroup ND-400 - summary


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Dx overall Student respondent Dx Factor 1 Dx Factor 2 Dx Factor 3 Dx Factor 4 Dx Factor 5
  research group ND
subgroup ND-400
Reading, Writing, Spelling Thinking & Processing Organization & Time Management Verbalizing & Scoping Working Memory
304.00 means 276.43 214.38 586.78 458.02 377.68
67.48 / 10.29 st dev / st err 118.78 / 18.11 103.08 / 15.72 151.32 / 23.08 218.03 / 33.25 206.19 / 31.44
284 < μ < 324 95% CI for μ 241 < μ < 312 184 < μ < 245 542 < μ < 632 393 < μ < 523 316 < μ < 439
            view this data as a chart: link to chart
88.42 #91518540 33.25 21.92 470.40 177.50 93.66
147.64 #76211159 181.19 9.41 629.38 199.69 0.00
178.81 #12161792 205.70 35.96 435.42 465.78 177.07
204.02 #68941653 68.46 359.54 100.68 5.55 79.27
222.44 #36617000 199.67 182.01 490.00 339.14 182.44
228.69 #30986732 207.65 140.21 522.49 307.58 275.37
232.27 #73897011 252.59 173.63 716.50 129.14 139.02
252.21 #34115096 296.79 38.17 466.50 57.89 506.83
260.33 #41501454 170.07 124.89 590.96 589.06 636.59
261.48 #74011406 28.27 323.81 620.73 330.78 390.24
274.57 #24931735 326.37 123.29 823.73 222.66 403.66
275.97 #61231849 128.86 254.66 627.85 422.50 351.22
276.18 #23894998 294.30 198.97 627.01 522.97 324.39
278.34 #21853014 126.98 141.78 569.94 1000.00 210.73
281.77 #89902966 227.22 366.48 507.91 530.55 110.00
286.15 #25893877 147.65 92.58 797.51 622.03 361.22
301.01 #15789237 315.46 138.49 720.73 453.44 449.51
302.82 #30113372 80.67 278.31 583.62 642.50 440.24
306.04 #65118727 288.88 259.95 504.69 539.22 293.90
308.84 #41750383 228.60 340.37 494.24 397.58 609.76
319.07 #43052413 226.98 150.62 440.90 797.66 643.90
321.56 #33549302 269.74 365.80 626.05 389.06 390.24
323.37 #18703444 495.68 77.05 506.72 686.72 386.34
326.09 #94875457 380.55 132.24 499.66 666.41 526.59
327.60 #39284633 149.55 264.36 634.35 259.84 835.37
334.95 #69417357 441.69 315.07 493.22 366.41 78.05
335.35 #21274561 239.50 259.25 542.49 645.86 317.07
345.19 #43811153 264.96 205.02 557.91 722.27 478.05
345.22 #39243302 455.11 146.58 757.06 666.41 382.93
345.28 #79451676 450.86 146.89 462.37 477.81 628.54
346.15 #21294241 377.72 319.86 576.27 404.77 473.17
351.79 #72989831 298.57 231.74 557.63 855.78 151.22
363.39 #51781498 320.78 143.77 541.36 445.31 841.46
363.58 #21591730 393.59 289.50 393.22 340.08 239.02
365.29 #11270227 402.23 234.57 793.33 500.00 235.12
368.74 #96620843 367.93 223.79 817.80 504.45 684.15
369.12 #55702780 262.47 339.16 772.32 433.98 395.12
372.13 #97326352 433.42 327.10 340.11 356.48 286.59
375.31 #81902739 346.01 324.57 770.00 285.31 470.73
380.40 #52641377 388.27 232.40 974.46 778.13 129.51
383.65 #84596013 332.90 236.30 638.14 638.67 593.90
386.09 #46690418 412.57 210.27 665.76 500.00 695.12
397.08 #10697171 393.21 424.22 597.57 409.22 301.22

 

student2. Academic Behavioural Confidence (ABC) Factors

 

A similar process of Principal Component Analysis has been executed on the data collected on Academic Behavioural Confidence, also through SPSS.

This has been prompted because a revised, 17-item ABC Scale has been established by Sander & Sanders (2009) following a re-inspection of the combined data from several of their earlier studies where ABC had been measured, and this was developed through PCA on data collected through their original 24-item scale. Their (relatively) large composite dataset (n = 865) was established by bringing together data collected from five earlier studies between 2001 and 2006 with psychology undergraduates (n=507) from one university in South Wales, together with a further dataset of ABC values obtained from first-year medical students at one HE institution in the Midlands collected in 2001 (n = 182) and an additional dataset of health care students from a new university in South Wales attending 6 different courses ranging from podiatry to dental health care (n = 176). The two, smaller of these three datasets are of a similar size to the number of respondents in this current project (n=166). There are both differences and similarities in the cohorts of students in Sander & Sanders' combined dataset when compared with features of my dataset. For example, a differences was that in the Sander & Sanders studies, students were all undergraduates whereas in my study all students in the university community were invited to participate in the research which produced an overall ratio between undergraduates and other students of 75% : 25%. ('undergraduates includes students attending foundation or access courses and 'other students' comprises post-graduates, research students and a very small number of others who did not disclose their study level (3)). However, a similarity was that in Sander & Sanders' datasets, students' previous academic achievement at A-level was recorded as across the complete range of grades and since this data was not requested in my study it is reasonable to assume that students who responded presented an equally wide range of prior academic achievement. In the Sander & Sanders' datasets, students were drawn from a narrow range of subject specialisms whereas in my study, subject studied at university was not recorded so it is also reasonable to assume that students from across the complete curriculum are as likely to have participated as not.

It was felt, therefore, that there are reasonable grounds for conducing PCA on my data because there may be bias in Sander & Sanders' analysis due to students being all undergraduates and all from similar subject specialisms whereas students in my datapool can be assumed to be representative of the complete student community at university as no data was collected in relation to their academic discipline. Hence the specific factor structure that my be revealed from my PCA may be more appropriate to use in my comparative analysis with Dyslexia Index as opposed to relying on the factor structure and revised 17-item ABC scale determined from the Sander & Sanders' collection of studies. Research data collected through the Academic Confidence Scale in an existing study (Corkery, 2011) was conducted to identify factors relevant to that data and these emerged as different from the factor analysis conducted by Sander & Sanders so a precedent is set for this approach to PCA within a research project.

 

Nevertheless, for this research project, the original 24-item ABC scale has been used in the main research QNR which has proved expedient since both the aggregated ABC-24 and ABC-17 values can be established for all the respondents in the datapool. In addition, data sifted through the Sander & Sanders factor structure can be compared with a similar process with factors established from my own PCA - indeed, a valuable exercise has been to compare which individual scale items map to which factors in each of the PCAs, the result of which is reported on the StudyBlog.

Briefly, the PCA on Academic Behavioural Confidence for this project's data resulted in 5 factors being identified and although the factor structure was not as simple as is desirable because a few dimensions (that is, ABC scale items) mapped to more than one factor, it is felt that in the context of this enquiry, there is justification for accepting the PCA outcomes. A report about this is presented also on the StudyBlog and this will be explored more fully in the final thesis. The 5 factors identified have been categorized as:

  • Study Efficacy
  • Engagement
  • Academic Output
  • Attendance
  • Debating

This process, in combination with the PCA on Dyslexia Index has enabled a very interesting matrix of effect sizes and t-test results to be compiled which identifies significant interrelationships between much more than the overall ABC and Dx values of all respondents in the project.

The table below sets out Hedges 'g' effect sizes and Student's t-test p-values for differences in ABC on a Dx factor-by-factor basis. This means that when respondents are sifted into the three respective research subgroups DNI, DI-600 and ND-400 according to each of the Dyslexia Index Factor values, that row of data presents the effect size differences (and t-test 'p' values) between the research subgroups for each ABC factor. For example, when sifting respondents into subgroups using Dx Factor 2 Processing as the criteria, the ABC Factor 2 Engagement showed an effect size of 0.43, considered as 'medium', between research subgroup DNI and DI-600, together with a very nearly significant difference between the sample means. In other words, students with unreported dyslexia-like profiles presented a measurably higher Engagement factor of Academic Behavioural Confidence than their identified-dyslexic peers.

Hedges 'g' has been used because this calculation uses a weighted mean process for pooling the standard deviations of each dataset being considered which is important when the datasets are of different sizes; Student's t-test for independent sample means is used in the one-tail format because in almost all cases, the mean ABC24 values for research subgroup DNI exceeded those for the (control) research subgroup DI-600.

factors summary table

It is important to understand that the process of sifting respondents' datasets according to Dx Factor results in different research subgroups.

For example: consider responent #96408084 from research group ND (students with no reported dyslexia) who presented an overall Dyslexia Index of Dx = 604.94. This value placed this respondent into the research subgroup of particular interest, DNI, which is students with an unreported dyslexia-like profile. However on a factor by factor basis, this respondent's Dx values are quite disparate ranging from Dx = 824.11 in Factor 1, Reading, Writing, Spelling, to Dx = 80 in Factor 4, Verbalizing and Scoping.

So on the basis of overall Dx value, this respondent is sifted into research subgroup DNI because at Dx = 604.94 this is above the boundary value of Dx > 592.5. However by looking at each of the respondent's Dx Factors. this dataset will only be sifted into research subgroup DNI for Factors 1 and 2, as Dx values for the remaining factors are below the boundary value of Dx = 592.5. Indeed, this respondent would actually feature in research subgroup ND-400 for Dx Factor 4 Verbalizing and Scoping.

Dx overall Student respondent Dx Factor 1 Dx Factor 2 Dx Factor 3 Dx Factor 4 Dx Factor 5
Reading, Writing, Spelling Thinking & Processing Organization & Time Management Verbalizing & Scoping Working Memory
604.94 #96408048 824.11 746.99 512.26 80.00 489.51


The table below summarises the research subgroup sample sizes and sample Dx means when respondents' datasets are sifted according to this criteria which also shows no significant differences between the Dx factor sample means for research subgroups DNI and DI-600 which supports the appropriateness of comparing other metrics, notably Academic Behavioural Confidence.

research subgroup sample sizes

 

Refer to the project StudyBlog for a wider discussion on data summaries presented on this page..