VALIDITY OF SAMPLING METHODOLOGY
47 The Applicant also challenges the decision of the Director on the basis that he sent the Committee copies of the 39 medical records together with his Director's Report which stated that it was open to the Committee to make a finding of inappropriate practice in relation to Dr Phan. It is submitted that this sample of records was not "random" because it contained items that had been previously examined by the Director and found to be examples of inappropriate practice. Therefore, the Applicant contends, the samples were not in accordance with the statutory procedure and were biased or skewed in such a way that any decision in relation to them must be invalid.
48 It is common ground that the Commission drew a preliminary random sample and then asked Dr Phan to produce the patient records relating to the item 23 services in that sample. I accept the view of Professor Nicholls that from a statistical point of view, it is irrelevant that the Committee looked at the same random samples and services as the Director. It was the Committee, rather than the Director, which had the authority to decide whether the sample disclosed inappropriate practice.
49 To support his position, Dr Phan has referred to the decision of Edmonds J in Mathews v Health Insurance Commission (2006) 90 ALD 49. In that case, his Honour decided that the Committee had erred in its sampling by failing to examine samples randomly drawn from a preliminary random sample as required by Health Insurance (Professional Services Review - Sampling Methodology) Determination 2000 (No. 1) ("the Determination"). The breach considered by his Honour was clear. The case was decided on the basis that the Committee had examined the first 30 services on lists of the first 40 services taken from lists of random samples furnished by the Commission. They were not therefore 'randomly drawn from the preliminary random sample' as required by s 8(a) of the Determination.
50 In the present case, the Committee - as it was entitled to do under s 106K(4) - used a sampling methodology which was not the subject of a Ministerial determination under s 106K(3). Instead, it used the sampling methodology which had been advised to be statistically valid by Professor Nicholls pursuant to s 106K(4) of the Act. The case of Mathews is clearly distinguishable from the present case, both on its facts and having regard to the controlling principles.
51 It was submitted by the Applicant in Mathews that the Committee's examination of 30 services in each MBS item of service under review from a list of 40 services provided to the Committee by the Director - which included services that had already been examined by the Director and found to be deficient and adverse to Dr Mathews - had the effect that the sample could no longer be considered to have been 'randomly drawn from the preliminary random sample.' His Honour did not find it necessary to determine this question and specifically left it open. However, he did indicate that there might be some suggestion that this allegation of error in the sampling process should be upheld.
52 It is important to note that, as discussed above, the Mathews case is distinguishable and that Edmonds J specifically refrained from deciding that particular question. The observation of his Honour is not binding on me. In my view, the sample used in the present case was in accordance with the requirements of the Act. The evidence is that the Commission drew a preliminary random sample and that the Director required the production of records which he examined. He concluded, for the reasons given by him in his Report, that it would be appropriate for him to refer the matter to a Committee. In examining the material and completing his Report, the Director did not decide that there was inappropriate conduct. That determination was left for the Committee to make following a hearing and having regard to the evidence adduced at that hearing. It is not correct to suggest that the Director had found that the samples had in fact given rise to inappropriate conduct. The fact that the Director examined and considered the records and forwarded them to the Committee does not affect their randomness when they were considered afresh by the Committee. The sample items retained their character as random samples and were not skewed or biased so that the Committee's decision should be considered invalid.
53 The next ground of invalidity raised relates to Professor Nicholls' memorandum addressed to Ms Goodspeed dated 5 March 2004. It is submitted that Professor Nicholls' memo demonstrates that the decision of the Committee was based on errors of law.
54 On 4 March 2004, Ms Goodspeed, who had been given the task of preparing a draft report for the Committee, sent an email to Professor Nicholls. She sought his advice as to whether it was unsafe to proceed with the proposed sampling methodology. In his reply of 5 March 2004, Professor Nicholls responded:
'Re: Request of 4 March 2004
From the information supplied I note:
· From the 17,970 item 23 services a random sample of 84 services have been examined (with 4 services being disregarded due to no records). The Committee found that of the remaining 80 services, 69 or 86% (rounded down) were considered inappropriate.
· Applying appropriate statistical techniques it can be shown that we can be 95% confident that the true percentage of inappropriate practice lies between 86% + 8%, that is the lower 95% confident limit is 78%. This value (78%) is to be chosen as the level of inappropriate practice (rather than 86%).
In conclusion, it is statistically valid to accept the conclusion based on the sample of 80 item 23 services that the level of inappropriate practice will be determined as 78%.
I confirm that I am a statistician accredited by the Statistical Society of Australia Inc. as required under subsection 106K(4) of the Act.'
55 I accept the explanation in relation to the sampling methodology as outlined by Professor Nicholls in his report dated 28 November 2005:
'3. The methodology on which the Determination is based is designed so the sampling procedure will result in the size of samples being determined so that if a particular sample is drawn then one can be 95% confident that the estimate of the percentage of inappropriate practice determined from the sample will be within +10% of the actual or true percentage of inappropriate practice. Once the estimated percentage of inappropriate practice has been determined by the Committee, this percentage is then reduced by 10% (the half width of the 95% confidence interval) to give the final percentage on which sanctions are to be based. This is to the benefit of the doctor.
4. An alternative approach, for a fixed sample size of 30 or more services, is to determine an estimate of the percentage of inappropriate practice. For this estimate, and the associated fixed sample size, it is then possible to determine the 95% confidence interval associated with the estimated level of inappropriate practice for the fixed sample size, and choose the lower bound of this confidence interval as the basis for which sanctions are to be based.
5. In the first approach the half width of the 95% confidence interval is fixed at 10%, and the size of the sample selected to guarantee that the difference between the estimated and true percentage of inappropriate practice is within this value, ie + 10%. The estimated percentage of inappropriate practice is then reduced by 10% for the imposition of sanctions.
6. In the second approach the sample size is fixed and the percentage of inappropriate practice determined from this sample. Based on the estimated percentage of inappropriate practice, a 95% confidence interval is then determined for this fixed sample. The lower limit of this confidence interval will then be taken as the basis of sanctions to be imposed.'
In his discussion of the present case, Professor Nicholls stated:
'24. [W]hat the Committee has done, in paragraph 30 of their final report, is to make their findings on a 'reduced final random sample of size 80 MBS item 23 services.' The Committee then pointed out that the half width of the confidence interval increased from 10% to 12%. That is, rather than calculate a final random sample as defined by the Determination and which will give a half width confidence interval of 10%, the Committee fixed the random sample at 80 and calculated the half width of the confidence interval (as 12%). As discussed above, provided the reduced sample is 30 or more, this is a statistically valid approach and leads to a statistically acceptable estimate of 46% to be used for the imposition of sanctions…
50. The Committee examined a random sample of size 80, and in its final deliberations, as reported in its final report, found 58% of these services to be inappropriate. This figure was then reduced by 12% , the lower limit of the 95% confidence interval, to give a figure of 46% which is to be used for the imposition of sanctions. The approach adopted by the Committee is statistically valid in accordance with subsection 106K(4) of the Health Insurance Act1973. In accordance with this subsection, the Committee adopted an approach approved by an accredited statistician as required by subsection 106K(4) of the Act.'
56 Dr Maxwell Stevenson, a statistician whose evidence was adduced by the Applicant, agreed that the alternative sampling plan supplied to the Committee by Professor Nicholls was a 'substantially valid' plan. However, he says that he did not thereby mean to indicate that he considered that the outcome was statistically valid. In his affidavit dated 6 March 2006, Dr Stevenson says that he checked the calculations and agreed that the conclusions presented in the final report of the Committee were statistically valid. However, he did not agree with the statement in the final report that the conclusions were arrived at by the sampling plan and as detailed in the Determination. He refers to the fact that one course of sampling action had been taken and a second course was then adopted in the analysis of the results in order to salvage the incorrect implementation of the first.
57 The principal difficulty with this challenge to the sampling process is that s 106K(4) of the Act specifically contemplates that the Committee can make use of an alternative sampling methodology to that prescribed in s 106K(3) if it has been advised by a statistician accredited by the Statistical Society of Australia Inc that the alternative sampling method is statically valid. Professor Nicholls' response to Ms Goodspeed's email dated 5 March 2004 clearly certifies that it was statistically valid for the Committee to accept the conclusion, based on a sample using 80 item 23 services, that the level of inappropriate practice would be determined at 78%.
58 The decision of the Committee was further contested by the Applicant on the basis that Dr Phan was unable to make any submission regarding the advice given by Professor Nicholls as Dr Phan was not notified that any such advice had been given. In my opinion, the Committee was not required by s 106K(4) to disclose the advice from Professor Nicholls. Under s 106K(4), it is open to the Committee to use any particular sampling methodology provided that the sampling methodology is the subject of the requisite advice prepared by a statistician qualified according to the section. The Committee is entitled to obtain the required advice at any stage of the decision-making process up to the time of the decision. There is no restraint on the changing of method, provided that the Committee makes use of a methodology that satisfies the requirements of s 106K(4).
59 In the present case, Professor Nicholls' advice constituted a condition precedent to the Committee's usage of a statistical tool or method of sampling. Once such an advice was obtained, the Committee was entitled to proceed on the basis of that certified or advised methodology. This is not a provision in respect of which there existed a duty to alert Dr Phan. The only issue which arises is whether, as a matter of fact, advice which complied with s 106K(4) was obtained by the Committee.
60 Furthermore, for reasons given above, the statutory hearing framework provides adequate opportunity for the practitioner to meet the substantive case brought against him. In this case, it is common ground that the conclusions in the final report of the Committee are statistically valid. In relation to the Committee's choice of methodology, it is important to note that like Professor Nicholls, Dr Stevenson is also a member of the Statistical Society of Australia and his confirmation on this point can be accepted. I am not persuaded that there is any constraint on the Committee proceeding on the basis of a sampling procedure which has been changed, provided that it uses a properly advised procedure and that the conditions of s 106K(4) are met. In particular, I do not accept the submission that if a previous method is considered inappropriate or invalid, it is impossible for an alternative method to be used by the Committee.