Formularios específicos del cálculo de cargas de viento

Reliability refers to the degree to which an assessment instrument produces stable and consistent results (Hughes, 2003:3). A research study is considered to meet the tests for reliability if other researchers can generate the same results using the same research instrument and methods under similar conditions (Babbie, 1995; Hughes, 2003).

As mentioned earlier in 3.5.1 the main research instrument, the PPVT-V has been proven to be both reliable and valid. Dunn and Dunn (2007:53) define reliability as ‘the precision of scores, that is, the degree to which they are free of measurement error.’ For the PPVT-V split-half reliability is high across the entire age and grade ranges, averaging .94 or .95 for each form; this is an indication of internal consistency reliability. The average test-retest correlation for the PPVT-V is .93 and indicates that the test is quite resistant to factors like fatigue, illness, differences in administration procedures or practise effects that might cause a learner to perform differently at different times (Dunn & Dunn, 2007). Therefore a separate reliability test for the context of this study was not deemed necessary.

During both the pre-tests and post-tests the researcher adhered closely to the instruction manual of the PPVT-IV on how to administer the test. In addition, the researcher did not influence the learners in any way during the assessments. The data were analysed in an unbiased manner (refer 3.9) and the results reflect the actual data obtained from the learners. The data from the PPVT-IV test are easily quantifiable and not open to subjective interpretation.

The qualitative data were obtained through interviews and observations and these data sets were analysed twice. This technique is called regrounding by Seliger and Shohamy (1989:186) and is a form of test-retest reliability. Regrounding involves the researcher going back to the data a second time and analysing the qualitative data a second time in order to confirm the themes and patterns observed the first time. Regrounding is used to enhance the reliability of data.

Although reliability is essential in any research study reliability alone is not sufficient — the research also needs to be valid. It is possible for a research study to be reliable but not valid (Hughes, 2003:50).

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3.6.2 Measurement validity

Validity indicates the degree to which a research study reflects the phenomenon which it claims to measure and refers to both the design and the methods of the research (Messick, 1996). Validity is therefore crucial to any research study. If the research instrument does not measure what it claims to measure, the results of the study are considered to be invalid. In other words, the results cannot be used to answer the research question(s) or to generalize the results and the study becomes useless and a waste of time and effort (Hughes, 2003).

Messick (1996:6) maintains that validity is not a property of the test itself, but of the meaning of the test scores. Validity refers therefore to the degree to which the conclusions made from a test are justified and accurate.

In this research study both qualitative and quantitative methods of obtaining data were used. The combination of these two methodologies allowed the researcher to form a more comprehensive picture of the research questions and, in the process, contribute towards the validity of the research (Seliger & Shohamy, 1989).

3.6.3 Research validity

There are two main types of validity, namely internal validity and external validity (Brown, 1988:36). Internal validity refers to the validity of the instruments and the test itself. According to Seliger and Shohamy (1989:95) ‘findings can be said to be internally invalid because they may have been affected by factors other than those thought to have caused them, or because the interpretation of the data by the researcher in not clearly supportable’. The main research instrument used in this research was the PPVT-IV and data from this test are easily quantifiable and not open to subjective interpretation.

External validity is concerned with the generalizability of the research — considerations of whether the research findings be generalized to a larger group or other contexts (Brown, 1988:40). Seliger and Shohamy (1989:95) state that ‘findings can be said to be externally invalid because [they] cannot be extended or applied to contexts outside those in which the research took place’. There are a number of factors that can influence external validity. According to Dornyei (2007:53), an important factor is the sample size. If the sample size is not big enough, the results

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of the research cannot be generalized to a broader population. In section 3.4.2 it is explained that, to compensate for small sample size and to build numbers, an external control group was added. There were consequently three groups of learners in the research study (as detailed earlier in 3.4.3 in this chapter).

Additionally, for the research to be valid it must be done under natural conditions. In other words, the data collection should take place in the usual context in which one would expect the interaction to take place. Lastly, for the research to be valid, the sample must be representative of the population to which the results can be generalized. In this research the sample population has the same characteristics as the wider population to which the research findings will be applied.

With regard to the use of the PPVT-IV, as stated in 3.5.1, the PPVI-IV has been proven to be valid and reliable, with reliability and validity coefficients in the range of .90. Assessments with a coefficient of .60 and above are considered acceptable and valid. The PPVT-IV is furthermore norm-referenced, standardized and easy to score. In the light of the above arguments, it is the contention of the researcher that this research study is both reliable and valid.

3.7 THE INTERVENTION

The research intervention took place for a period of two whole school terms. It consisted of interactive reading sessions for the Experimental Group every Tuesday and Friday morning. Each session lasted about 30 minutes and was done by the Experimental Group’s class teacher (refer 3.7.4 for information on teacher training).

3.7.1 Reading

The interactive storybook reading sessions were a vital component of the intervention. The literature review in Chapter 2 demonstrates that reading to learners in their L2, even at a very young age, has the positive effect of not only improving their comprehension, but also expanding their vocabulary (Beck et al., 1982; Justice et al., 2005; Biemiller & Boote, 2006; Roberts, 2008). Research (Ard & Beverly, 2004; Beck & McKeown, 2007; Roberts, 2008) has found that the most effective way to read aloud to learners is with enthusiasm and to share enthusiasm for reading with the learners. This study aimed to do just that, to read to learners with enthusiasm and in this way to build learners’ enthusiasm for reading. In addition, it is

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important that the reader is a fluent and competent reader as the reader must become a model of what good reading sounds like. One of the goals of the intervention reading sessions was to make it a positive and likable experience for the learners, with the intention that it would lead to them having a positive attitude towards reading and in turn be more susceptible towards the L2 and vocabulary acquisition in the L2.

The first two reading sessions of the intervention were done by the researcher. Learners were eager and attentive during these sessions and consequently the researcher found the sessions relatively easy and the experience both enjoyable and rewarding. These sessions were performed by the researcher as it served as a practical demonstration for the teacher and formed part of the teacher training (refer 3.7.4). The researcher explained to the teacher exactly what the reading sessions should entail, and demonstrated this in the first two reading sessions. The vocabulary instruction methods that were used in the intervention, are discussed in detail in 3.7.3. The third reading session was done by the teacher under supervision of the researcher and thereafter, by the teacher on her own.

A few additional points must be taken into account. Firstly, the choice of reading material is vital (Lesaux et al., 2010). It is important that the books are not too difficult for learners to understand, but at the same time also not too simplistic to prevent learners from becoming bored and losing interest. As stated earlier, it is important to read with fluency and it is therefore advisable to familiarize oneself with the reading material before reading it to the learners. Further, as was discovered during the pilot study (refer 3.11.5), it is important to make sure that the learners are physically comfortable when reading to them, as this will contribute to them sitting still and listening. Lastly, the reader must become a ‘seller’ of reading to the learners, s/he must be enthusiastic and animated; and must show the learners the wonderful treasures that are available in books (Ard & Beverly, 2004). The format and structure of the reading sessions will be discussed in more detail in 3.7.3.

3.7.2 Materials

Choosing the reading material for the intervention proved more problematic than expected. However, after the pilot study (refer 3.11) the researcher had a better indication of the level and standard of the learners’ English vocabulary. This, as well

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as the fact that Grade 1 L2 vocabulary are mainly Tier 1 words and that concrete concepts with pictures are easier to learn, had to be taken into consideration when determining the storybooks that were to be used in the research (McKeown & Beck, 2011).

During the two reading sessions the researcher had with learners before the start of the intervention (refer 3.11.2) the researcher realised that the stories the Grade 1 learners could understand with their limited L2 vocabulary proved to be too one- dimensional and simplistic to sustain their interest. When this happened, learners started fidgeting and stopped paying attention to the reading. On the other hand, more advanced stories contained more challenging vocabulary which made it harder for learners to follow. The researcher had to find some compromise - stories that would be attention-grabbing without being too difficult for learners to understand. Another factor that had to be considered when choosing reading material was the frame of reference of the learners. It is important to try and find storybooks that the learners could identify with and find relevant and interesting. Also, after speaking with the teacher and doing the two reading sessions as part of the pilot study, the researcher realized that the Grade 1 leaners of School A had very little exposure to stories and books.

One way in which the researcher tried to solve the problem of identifying suitable reading material was by using stories that might be familiar to learners. The researcher asked for the teacher’s input and discussed the learners’ frame of reference with her. Both the teacher and the researcher felt that the popular (and age old) stories that have universal appeal for children would be appropriate to use as reading material for the intervention. These included fairy tales with moral lessons like The princess and the frog and Little Red Riding Hood. Another factor that had to be kept in mind is that, as Dickinson and Smith (1994:112) note, the topic of a book is very important as it must not only be of interest to the learners, but must also generate discussions around and about the topic.

The difficulties in vocabulary comprehension were compensated for by translating and explaining the more difficult and unfamiliar words during the reading sessions. Each book chosen for the intervention also contained numerous big, colourful and fun illustrations. To further assist the teacher, and because the school had very few

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resources, the researcher not only chose the reading material, but also supplied the teacher with copies of the books. Books that were read were, amongst others: King Midas (Al Perkins), The Frog Princess (Elizabeth Baker), Little Red Riding Hood (Candice Ransom), The Adventures of the Busy Bears (Poppy Welsh), The Kiss that Missed (David Melling), Q Pootle 5 in Space (Nick Butterworth), Alley Dogs (Lesley Rees), The things I love about pets (Trace Moroney), The things I love about friends (Trace Moroney) and Cinderella (Marcia Brown).

In addition, the researcher encouraged the teacher to expose the learners in the Experimental Group to additional literacy materials during the intervention. Some of the material (like the posters and flash cards) were provided by the researcher and others (like the worksheets) were drawn up by the teacher. The additional literacy material consisted of the following:

 Posters – Big, colourful and lively. One mathematical poster showing the various shapes in different colours, a poster of farm animals and a poster of fruit.

 Worksheets – Fun and stimulating activities containing the words and concepts discussed in the reading sessions to consolidate vocabulary learning.

 Big Books – A5 books consisting of big, vibrant pictures that prompt discussions and contain very little text.

 Flash Cards – depicting various animals, fruits and everyday objects.

These additional visual materials were mainly used as part of the follow up activities, after the storybook reading had taken place. Posters containing shapes, for instance, helped learners to identify abstract mathematical concepts by matching visual shapes and symbols with the vocabulary. In this way the follow-up activities incorporated different senses and this helped to reinforce vocabulary (Roberts, 2008).