Mitsubishi P91W Instruction Manual download pdf (Page 42)

ChemiDoc MP with Image Lab Software | Acquiring Images

REGRESSION METHODS

A regression method is used to calculate the molecular weight of the unknown

bands. The software uses the relative front and molecular weight values of the

standard bands to calculate the standard curve. This standard curve is then

used to calculate the values of the unknown bands. The shape of the standard

curve is based on the selected regression method. Choose one of the four

regression methods listed below.

If you do not have enough data points for the selected method, the molecular

weight of the unknown bands are not calculated.

13. Select the appropriate method for the gel type:

• Gradient gels: The Linear (semilog) regression method works well

for these gels because the mobility of the bands is linear to the log

of their molecular weight. As an alternative, the point-to-point

(semilog) method can be used if the R

value is not sufficient

• Fixed percentage gels: These gels have a nonlinear relationship

between the mobility and the molecular weight. For these gels,

choose the logistic or cubic spline regression method

You can check how well each regression method fits the data in the standard

curve window (see Standard Curve on page 65 for more information). The

linear (semilog) regression method provides a measurement that describes

how well the standard curve fits the data R

value. The closer the R

value is

to 1.0, the better the data fit the standard curve.

The molecular weight of each band is displayed in the analysis table in the

Mol. Wt./Base Pair column. Refer to page 99 for more information about

molecular weight.

For information about the calculations behind the regression methods, see

Appendix E. Regression Calculation Methods.

Tab l e 1 .

Regression Method Minimum number of standard bands

Linear (semilog) 2

Point-to-point (semilog) 2

Logistic 5

Cubic spline 5

1 2 ... 37 38 39 40 41 42 43 44 45 46 47 ... 143 144

No comments

Mitsubishi P91W Instruction Manual Page 42