qPCR fold change (ddCt): practice problems Work out the result for qPCR fold change (ddCt). Every answer here is computed by the same tested calculator the rest of the site uses, so a solution can never drift away from the maths.
Problem 1 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 20 Treated target Ct (SD): 0.75 Treated reference Ct (mean): 21 Treated reference Ct (SD): 0.15 Control target Ct (mean): 23 Control target Ct (SD): 0.25 Control reference Ct (mean): 17 Control reference Ct (SD): 0.15 Show the answer and the working Fold change 128x (up), 95% band 72.58 to 225.74.
ΔCt treated / control: Ct_target − Ct_ref = -1 / 6 ΔΔCt: ΔCt_treated − ΔCt_control = -7 ± 0.819 Fold change: 2^(−ΔΔCt) = 128 (72.578 to 225.743) Open this in the calculator to change the numbers.
Problem 2 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 20 Treated target Ct (SD): 0.3 Treated reference Ct (mean): 21 Treated reference Ct (SD): 0.5 Control target Ct (mean): 21.5 Control target Ct (SD): 0.4 Control reference Ct (mean): 20 Control reference Ct (SD): 0.15 Show the answer and the working Fold change 5.66x (up), 95% band 3.43 to 9.34.
ΔCt treated / control: Ct_target − Ct_ref = -1 / 1.5 ΔΔCt: ΔCt_treated − ΔCt_control = -2.5 ± 0.723 Fold change: 2^(−ΔΔCt) = 5.657 (3.428 to 9.336) Open this in the calculator to change the numbers.
Problem 3 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 20 Treated target Ct (SD): 0.5 Treated reference Ct (mean): 16 Treated reference Ct (SD): 0.5 Control target Ct (mean): 22 Control target Ct (SD): 0.25 Control reference Ct (mean): 16 Control reference Ct (SD): 0.15 Show the answer and the working Fold change 4x (up), 95% band 2.35 to 6.8.
ΔCt treated / control: Ct_target − Ct_ref = 4 / 6 ΔΔCt: ΔCt_treated − ΔCt_control = -2 ± 0.765 Fold change: 2^(−ΔΔCt) = 4 (2.354 to 6.797) Open this in the calculator to change the numbers.
Problem 4 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 23 Treated target Ct (SD): 0.2 Treated reference Ct (mean): 17.5 Treated reference Ct (SD): 0.75 Control target Ct (mean): 25 Control target Ct (SD): 0.1 Control reference Ct (mean): 17 Control reference Ct (SD): 0.15 Show the answer and the working Fold change 5.66x (up), 95% band 3.26 to 9.83.
ΔCt treated / control: Ct_target − Ct_ref = 5.5 / 8 ΔΔCt: ΔCt_treated − ΔCt_control = -2.5 ± 0.797 Fold change: 2^(−ΔΔCt) = 5.657 (3.256 to 9.828) Open this in the calculator to change the numbers.
Problem 5 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 23 Treated target Ct (SD): 0.3 Treated reference Ct (mean): 17.5 Treated reference Ct (SD): 0.2 Control target Ct (mean): 21 Control target Ct (SD): 0.3 Control reference Ct (mean): 17 Control reference Ct (SD): 0.1 Show the answer and the working Fold change 0.35x (down), 95% band 0.25 to 0.49.
ΔCt treated / control: Ct_target − Ct_ref = 5.5 / 4 ΔΔCt: ΔCt_treated − ΔCt_control = 1.5 ± 0.48 Fold change: 2^(−ΔΔCt) = 0.354 (0.254 to 0.493) Open this in the calculator to change the numbers.
Problem 6 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 22 Treated target Ct (SD): 0.3 Treated reference Ct (mean): 18 Treated reference Ct (SD): 0.5 Control target Ct (mean): 23 Control target Ct (SD): 0.4 Control reference Ct (mean): 21 Control reference Ct (SD): 0.25 Show the answer and the working Fold change 0.25x (down), 95% band 0.15 to 0.42.
ΔCt treated / control: Ct_target − Ct_ref = 4 / 2 ΔΔCt: ΔCt_treated − ΔCt_control = 2 ± 0.75 Fold change: 2^(−ΔΔCt) = 0.25 (0.149 to 0.42) Open this in the calculator to change the numbers.
Problem 7 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 19 Treated target Ct (SD): 0.3 Treated reference Ct (mean): 17.5 Treated reference Ct (SD): 0.2 Control target Ct (mean): 22 Control target Ct (SD): 0.25 Control reference Ct (mean): 18.5 Control reference Ct (SD): 0.4 Show the answer and the working Fold change 4x (up), 95% band 2.65 to 6.04.
ΔCt treated / control: Ct_target − Ct_ref = 1.5 / 3.5 ΔΔCt: ΔCt_treated − ΔCt_control = -2 ± 0.594 Fold change: 2^(−ΔΔCt) = 4 (2.651 to 6.037) Open this in the calculator to change the numbers.
Problem 8 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 21 Treated target Ct (SD): 0.75 Treated reference Ct (mean): 18 Treated reference Ct (SD): 0.2 Control target Ct (mean): 22 Control target Ct (SD): 0.4 Control reference Ct (mean): 18 Control reference Ct (SD): 0.75 Show the answer and the working Fold change 2x (up), 95% band 0.9 to 4.44.
ΔCt treated / control: Ct_target − Ct_ref = 3 / 4 ΔΔCt: ΔCt_treated − ΔCt_control = -1 ± 1.151 Fold change: 2^(−ΔΔCt) = 2 (0.901 to 4.442) Open this in the calculator to change the numbers.
Problem 9 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 23 Treated target Ct (SD): 0.3 Treated reference Ct (mean): 17 Treated reference Ct (SD): 0.2 Control target Ct (mean): 22 Control target Ct (SD): 0.5 Control reference Ct (mean): 17 Control reference Ct (SD): 0.2 Show the answer and the working Fold change 0.5x (down), 95% band 0.32 to 0.78.
ΔCt treated / control: Ct_target − Ct_ref = 6 / 5 ΔΔCt: ΔCt_treated − ΔCt_control = 1 ± 0.648 Fold change: 2^(−ΔΔCt) = 0.5 (0.319 to 0.784) Open this in the calculator to change the numbers.
Problem 10 qPCR fold change (ddCt) Work out the result for qPCR fold change (ddCt).
Treated target Ct (mean): 18 Treated target Ct (SD): 0.3 Treated reference Ct (mean): 17 Treated reference Ct (SD): 0.75 Control target Ct (mean): 22.5 Control target Ct (SD): 0.1 Control reference Ct (mean): 18 Control reference Ct (SD): 0.15 Show the answer and the working Fold change 11.31x (up), 95% band 6.37 to 20.08.
ΔCt treated / control: Ct_target − Ct_ref = 1 / 4.5 ΔΔCt: ΔCt_treated − ΔCt_control = -3.5 ± 0.828 Fold change: 2^(−ΔΔCt) = 11.314 (6.375 to 20.079) Open this in the calculator to change the numbers.
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Open the qPCR fold change (ddCt) calculator