Statistical Analysis for Education and Psychology Researchers

Example 5.2: Estimating Sample Size for Difference in Proportions (Independent) A review of the reading recovery (RR) programme ...

magnitude of difference) would suggest a smaller sample size is required. The following two lines of ‘data’ are entered in the p ...

phonological decoding when processing unfamiliar written words. Phonological decoding of unfamiliar written words is when a read ...

n 11 =8 n 12 =3 n 13 =1 n 21 =4 n 22 =8 n 23 =0 then pie1=n 11 /(n 11 +n 12 )=0.727 and pie2=n 21 /(n 21 +n 22 )=0.333. When the ...

means (independent groups) We can use the same SAS programme to determine the required sample size to achieve 80 per cent power, ...

The first question relates to determination of power (set to −9 in the programme) given an alpha of .001, a difference in means ...

input power alpha diff sd n; cards; −9 0.001 0.6 3.676 828 0.80 0.05 0.8 20.715 − 9 ; Figure 5.7: SAS code for POWER3 programme ...

in teachers’ perceptions about student misbehaviour before and after the intervention because the correlation between pre- and p ...

Examining Data Distributions Example 5.6: Distributions of Three Reading Scores A PhD student collected data on a number of read ...

Figure 5.9: Percentage correct score of syntactic awareness (difficult reading passage) with a positive skew The variable ‘corrd ...

kurtosis (too few values under one tail of the distribution) and the relative positioning of the mean, median and mode, i.e., mo ...

Figure 5.10: Percentage correct score of syntactic awareness (easy reading passage) with a negative skew The variable ‘corre’ is ...

kurtosis (light tail), that is, too few values under the right tail of the distribution and the relative positioning of the mean ...

Figure 5.11: Vocabulary (raw scores) approximate normal distribution The variable vocabulary is approximately normally distribut ...

Interpretation of the Test Statistics W:Normal (or D:Normal) In SAS the normal option in PROC UNIVARIATE tests the null hypothes ...

steeply so that high ranked scores correspond to larger than expected (the straight line) standardized scores. To see whether th ...

What Transformations to Use Positively skewed or when the standard deviation is proportional to the mean There are two possible ...

Statistical analysis for education and psychology researchers 152 ...

Figure 5.12: Histogram and normal probability plot for log transformed variable ‘CORRD’—percentage correct difficult reading pas ...

has the effect of moving both high and low percentage scores towards the middle of a distribution. The original distribution for ...