Triple Test Cross Analysis

Triple test cross analysis online with additive, dominance and epistasis tests.

Open the Triple Test Cross Analysis calculator

When to use it

Use the Triple Test Cross (Kearsey and Jinks 1968) when you want a single design that simultaneously detects epistasis, estimates additive variance, and estimates dominance variance from F2 lines crossed to two inbred parents and their F1. The TTC is more powerful than generation mean analysis for detecting epistasis because it uses individual line data rather than only generation means.

When NOT to use it

Do not use when only generation means (no individual line data per F2 derivative) are available; use generation mean analysis. Do not use when fewer than about 25 F2 lines were tested; the analysis becomes unstable. The TTC is heavier on field labour than a generation-mean trial; for small studies the generation-mean approach is more practical.

What you get

ANOVA partition of the TTC sum of squares with sources Sums (additive), Differences (dominance), and Sums-by-Differences (epistasis), each with F tests against the appropriate error. Per-source variance components. Estimates of additive variance D and dominance variance H1, H2.

How to interpret the output

A significant Sums-by-Differences F is direct evidence for epistasis. The Sums F tests additive variance; a large F indicates substantial additive variance available for selection. The Differences F tests dominance variance. Kearsey and Jinks (1968) is the original; Kearsey and Pooni (1996) gives the modern textbook treatment.

Common pitfalls

Skipping the epistasis test (Sums-by-Differences) and reading additive and dominance estimates as if epistasis were absent.
Using too few F2 lines; the design needs replication to estimate variance components.
Treating the variance estimates as fixed properties of the population (they are estimates with sampling error).

Try it in StatVeda

The Triple Test Cross Analysis engine runs entirely in the browser. No signup, no install, no data sent to a server. Paste your data, hit Run, copy the output.

Open Triple Test Cross Analysis

References

Kearsey, M. J. and Jinks, J. L. (1968). A general method of detecting additive, dominance and epistatic variation for metrical traits. I. Theory. Heredity, 23(3), 403 to 409.
Kearsey, M. J. and Pooni, H. S. (1996). The Genetical Analysis of Quantitative Traits. Chapman and Hall, London.
Mather, K. and Jinks, J. L. (1971). Biometrical Genetics, 2nd edition. Chapman and Hall, London.