Appendix B Calculations for the BeLPT

DOE-SPEC-1142-2001

APPENDIX B

CALCULATIONS FOR THE BeLPT

As the result of biological variability in the well counts, there are different levels of uncertainty

present in each BeLPT. This internal variability is described by the standard deviation of the

natural logarithms (Ln) of well counts, and is equivalent to the coefficient of variation on the

original scale. The "internal analysis" of the BeLPT is based on estimates of the Ln(SI)s and

their standard errors. These estimates are calculated using the least absolute values (LAV)

method described in detail in Environmental Health Perspectives Supplement, 1996 (EHP96).

This approach only requires the ability to calculate medians and can be done in a spreadsheet

(e.g., Excel) or statistical program (e.g. Splus). A summary of the assumptions for this analysis

and alternative methods that could be used are provided in Section B-8. Results of using these

methods for the example BeLPT data are provided in reports listed in Section B.9.

The example that follows is a tritiated thymidine BeLPT using the assay design described in

EHP96 and is provided to illustrate the general procedure. The only quantity that depends on the

assay design (i.e., the number of replications for the control wells and/or the treated wells) is the

standard error of the Ln(SI) in step B.5. The same methods can be used for the BAL-LPT. The

standardized Ln(SI)s are used to determine if stimulated cells show a positive response. They

can also be used in the evaluation of new technicians (see 5.3.4) and in the selection of a new

serum (5.3.1).

B.1. Calculate the Ln of the well counts in Table B-I and record in columns 2-5 of Table B-II.

Table B-I

BeLPT Count Data

Treatment Group

Well Counts

Day5 controls

1220

2391

1774

947

Day5 controls

1499

1568

1410

1131

Day5 controls

969

2265

1743

728

Day5 Be1

1777

1890

1702

1885

Day5 Be10

3368

7221

1473

3097

Day5 Be100

3631

3655

2452

1634

Day7 controls

3616

17410

3989

3144

Day7 controls

669

1257

1497

4460

Day7 controls

2897

4174

1366

1152

Day7 Be1

1670

2186

629

1264

Day7 Be10

330

598

254

264

Day7 Be100

3611

4436

14452

14892

PHA

102160

44223

59344

51088

CONA

115673

104146

252237

159421