Preliminary SRT and SLOPE Final Form SRTs and SLOPE

4 Primary Data Exploration and Analysis

4.1 Relationship Between SRT and SLOPE

4.1.1 Preliminary SRT and SLOPE

First we explore the relationship between SLOPE and the total score on the preliminary SRT sentences. The Preliminary form of the SRT consisted of sixty-three sentences of varying complexity. Figure 1 shows a plot of the raw SRT total score against SLOPE for the thirty-one subjects who had valid scores on both tests. There appears to be a reasonable relationship, which shows some curvature, however, leading to a lack of discrimination at upper levels. There is some scatter, especially around SLOPE level 2. The information displayed in figure 1 is summarised in the following cross-tabulation. Table 1. Total score on preliminary SRT rows versus SLOPE level cols Total Score on Preliminary SRT SLOPE Level 1 1+ 2 2+ 3 3+ 4 20–29 1 0 0 30–39 0 0 0 40–49 0 1 50–59 1 1 60–69 0 0 0 70–79 0 1 1 80–89 0 2 90–99 0 1 100–109 0 1 1 1 0 0 110–119 0 2 3 3 0 0 120–129 3 2 130–139 0 2 1 140–149 0 1 1 150–159 1 The table and the graph show that those with a lower SLOPE rating do tend to score lower on the SRT. However, for those people scoring 120 or more on the SRT, the SRT score does not appear to discriminate between the different higher SLOPE levels. In interpreting the graph and the table, we must remember that we are comparing the results on sixty-three sentences rather than a shorter final form with SLOPE which would not normally be used in routine calibration of an SRT. Let’s now see how SLOPE levels compare with the results obtained on the Fig. 1 X = SLEV Y = PSVS1 20 40 60 80 100 120 140 160 180 1 2 3 4 5 SLOPE LEVEL TOTAL SCORE ON PRELIMINARY SRT final form fifteen-sentence SRTs A and B, remembering that sentences for the two Final Form SRTs were chosen from the sentences of the Preliminary form on the basis of the RPE-based Discrimination Index DI and Difficulty Level DL as described in Radloff 1991. The DI and DL results are shown in appendix 3.

4.1.2 Final Form SRTs and SLOPE

Figures 2 and 3 show how the scores obtained on final form SRTs A and B compare with SLOPE level, for the forty-eight subjects who had valid scores on these tests, and on the RPE, i.e, excluding scores for those subjects rated by RPE raters 12 and 15. This ensures that in all the comparisons between final form SRTs A and B, SLOPE, and RPE, we are using results from the same population of forty-eight subjects. There is no reason to suppose, however, that the SLOPE scores or scores on SRTs A and B were flawed for those fifteen additional subjects rated by RPE raters 12 and 15. Although these are not included in the tables and graphs shown here, inclusion of their results confirmed the conclusions arrived at based on the forty-eight subjects used for the analysis. Tables 2 and 3 summarise the behaviour illustrated in figures 2 and 3. Fig. 2 X = SLEV Y = SRTTSA1 5 10 15 20 25 30 35 40 45 50 1 2 3 4 5 SLOPE LEVEL TOTAL SCORE SRT A Table 2. Total score on Final Form SRT A rows versus SLOPE level cols Total Score on Final form SRTA SLOPE Level 1 1+ 2 2+ 3 3+ 4 4+ 0–2 3–5 6–8 9–11 1 0 0 0 12–14 0 15–17 1 2 0 0 18–20 0 1 1 21–23 0 2 24–26 0 1 2 1 27–29 0 1 2 30–32 0 2 0 0 0 0 0 33–35 0 2 4 5 1 2 36–38 1 4 1 1 39–41 1 4 2 0 0 42–44 0 0 1 1 1 Fig. 3 X = SLEV Y = SRTTSB1 5 10 15 20 25 30 35 40 45 50 1 2 3 4 5 SLOPE LEVEL TOTAL SCORE ON SRT B Table 3. Total score on Final Form SRT B rows versus SLOPE level cols Total Score on Final Form SRTB SLOPE Level 1 1+ 2 2+ 3 3+ 4 4+ 0–2 3–5 6–8 9–11 1 0 0 0 12–14 0 15–17 0 1 0 0 18–20 0 2 0 0 21–23 1 1 4 1 24–26 0 0 0 0 27–29 0 3 3 30–32 0 1 2 1 0 0 0 33–35 0 1 4 1 2 36–38 3 4 2 1 39–41 1 2 1 1 42–44 2 2 0 0 From these tables we see that the SRT is only useful to discriminate at the lower levels. There is a very wide spread of SRT scores at SLOPE level 2+. A person with a score on either of the SRT tests in the range 30–35 could have any SLOPE level from 2 to 4. For SLOPE levels 3 and above, there is no trend at all in the SRT scores. The majority of our subjects were assigned SLOPE levels 2 to 3, whereas we could have done with more subjects at the extremes. It is apparent, however, that someone with a score 35 is most likely to have an assigned SLOPE level of 3 or above, and that someone with a score of 30 is most likely to have an assigned SLOPE level below 3. Those scoring 30–35 had a wide range of assigned SLOPE levels; for subjects scoring in this range, no reliable conclusions about L2 proficiency levels can be drawn.

4.2 Relationship Between RPE and SLOPE