Table 2 Differences in pupils’ performance on each of the four decoding tasks across the three instructional years

From: Inadequate foundational decoding skills constrain global literacy goals for pupils in low- and middle-income countries

Task

Contrast

Mean point estimate and 95% HDI of the posterior distribution

Difference in means

Difference in s.d.

Effect size

Letter name identification (correct letter names per minute)

Year 2 versus year 1

8.49

[3.06, 13.80]

4.58

[0.56, 8.57]

0.47

[0.16, 0.78]

Year 3 versus year 2

20.66

[14.10, 27.41]

7.47

[2.78, 12.35]

0.77

[0.51, 1.04]

Letter sound identification (correct letter sounds per minute)

Year 2 versus year 1

6.91

[4.69, 9.17]

2.41

[0.59, 4.19]

0.70

[0.45, 0.96]

Year 3 versus year 2

−1.30

[−3.70, 1.00]

−1.05

[−2.95, 0.85]

−0.13

[−0.37, 0.10]

Non-word reading (correct non-words per minute)

Year 2 versus year 1

4.39

[3.23, 5.54]

3.50

[2.63, 4.39]

0.76

[0.56, 0.95]

Year 3 versus year 2

6.01

[4.19, 7.84]

3.63

[2.35, 4.97]

0.65

[0.45, 0.86]

Oral reading fluency (correct words per minute)

Year 2 versus year 1

6.37

[4.98, 7.77]

5.52

[4.39, 6.68]

0.82

[0.64, 0.99]

Year 3 versus year 2

10.12

[7.65, 12.70]

6.69

[4.88, 8.55]

0.67

[0.50, 0.85]

  1. For each parameter, we report the mean point estimate (top row in the result columns) and the 95% HDI (bottom row) of the posterior distribution (that is, a range of credible values for the effect of interest). The effect size is Cohen’s d19 computed from the posterior distribution, with the mean representing the mean standardized distance between pupils’ performance across the instructional years and the 95% HDI representing the uncertainty around this point estimate.
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