Quality of scales

A) Cronbach’s alpha

Cohen et al. (2007, p. 506) argue that an alpha coefficient higher than .90 can be considered as very highly reliable, .80-.90 highly reliable, .70-.79 reliable, and .60-.69 marginally/minimally reliable. Following this categorisation, Table 3.11 suggests reliability for measuring the role of evaluators in providing written feedback, and discussion with teachers before and after observation. The role of head teacher, the role of inspector and the role of head of department were only .70 and above, which indicates that the scale is reliable.

Table 3.11 also shows a range of a maximum of .82 to measure rating the value of the inspector’s role, which had high reliability, .78 for rating the value of the head teacher’s role, and .77 for rating the value of the head of department’s role that had reliability.

Table 3.11: Cronbach’s alpha of scales for the involvement of evaluators

Scale Number of Items Cronbach's Alpha

The Role of Evaluators

Head Teacher _{3 .70}

Inspector _{3 .73}

Head of Department _{3 .70}

The Value of Evaluators’ Role

Head Teacher _{3 .78}

Inspector _{3 .82}

Head of Department _{3 .77}

Table 3.12 shows Cronbach’s alpha if the item was deleted for the involvement of evaluators (role and rating the value). The results show that none of the values is greater than the current alpha, except when the item ‘You have had a discussion before a

classroom observation’ is deleted from the component, then Cronbach’s alpha increases from 0.813 to 0.892. However, this researcher decided to retain all items in the scale as this gives it more breadth.

Table 3.12: Cronbach's alpha if item deleted in scales for the involvement of evaluators

The Role of Evaluators Corrected

Item-Total Correlation Cronbach's Alpha if Item Deleted Head Teacher

You have had a discussion before classroom observation .366 .813 You have had a discussion after classroom observation .604 .507

You have received written feedback .614 .491

Inspector You have had a discussion before classroom observation .366 .862

You have had a discussion after classroom observation .647 .539

You have received written feedback .694 .481

Head of Department

You have had a discussion before classroom observation .382 .826 You have had a discussion after classroom observation .587 .537

You have received written feedback .633 .475

The Value of Evaluators’ Role Corrected

Item-Total Correlation Cronbach's Alpha if Item Deleted Head Teacher

You have had a discussion before classroom observation .484 .878 You have had a discussion after classroom observation .708 .623

You have received written feedback .709 .619

Inspector You have had a discussion before classroom observation .524 .892

You have had a discussion after classroom observation .737 .675

You have received written feedback .758 .653

Head of Department

You have had a discussion before classroom observation .470 .866 You have had a discussion after classroom observation .685 .585

You have received written feedback .669 .597

Following this categorisation, Table 3.13 suggests reliability is high for the scale for the current system supports the development of performance (.97), and also for the scale for the current system supports the awarding of promotions and rewards (.83)

Table 3.13: Cronbach’s alpha for scales for the current system supports teachers

Scale Number of

Items

Cronbach's Alpha

The system supports the development of performance 12 .97

The system supports the awarding of promotions and rewards 2 .83

Table 3.14 shows Cronbach’s alpha if items are deleted for the two mentioned scales. The results show that none of the values is greater than the current alpha of the whole scale, and if an item is deleted, Cronbach’s alpha does not change significantly.

Table 3.14: Cronbach's alpha if items are deleted for scales for the current system supports teachers

The system supports the development of performance Corrected Item-Total Correlation

Cronbach's Alpha if Item Deleted It has improved the deep understanding of content that you teach .806 .969

It has assisted you with better use of pedagogies .865 .968

It has given you a much clearer understanding of lesson planning .881 .967 It has given you a much clearer understanding of what constitutes effective

teaching

.878 .967

It has revealed the weaknesses of your performance .838 .968

It has played a significant role in determining strengths of your performance .865 .968 It has affected your organisation of activities in the classroom .821 .969 It has affected your dealing with students' discipline and behaviour problems .840 .968 It has affected your ability to motivate students in terms of their learning .826 .969 It has affected your ability to deal with individual differences between students .829 .969

It has affected your continuous assessment of students’ learning’ .836 .938

It has affected your providing students with effective feedback .839 .968

The system supports the awarding of promotions and rewards Corrected Item-Total Correlation

Cronbach's Alpha if Item Deleted It has affected your rewards in terms of an annual bonus or salary increase .712 .

It has impacted you in terms of your promotions .712 .

B) Ceiling and flooring effects

Figure 3.2 shows no ceiling or flooring effects for the scale regarding support of the system for performance development. For the ceiling scores pile up at 4 (the average responses) applying to over 60% of participants. By contrast, a score pile up at 2.5 (the average response) represents a downward direction.

Figure 3.2: Histogram of ceiling and flooring effect for the system supports the development of performance

Figure 3.3 shows no ceiling or flooring effects for the scale regarding the awarding of promotions and rewards. For the ceiling scores pile up at 4 (the average response), while the scores pile up at 1.5 (the average response) as a downward direction.

Figure 3.3: Histogram of ceiling and flooring effect for the system supports the awarding of promotions and rewards

With regard to the ceiling and flooring for the involvement of evaluators in the current system (evaluators’ role and rating the value of their role), the data did not show the ceiling and flooring effects (see the histograms in Appendix 23). This researcher therefore concluded that the scales had successfully avoided both floor and ceiling effects.