Which are the conditions for using parametric test for data analysis?

Parametric tests require that the data follow a normal distribution, that the dependent variable is measured on an interval or ratio scale, and that variances are homogeneous, so statements 2, 4 and 5 apply.

A sample size greater than thirty is a rule of thumb, not a strict parametric assumption.

Requiring that all parameters be known is false, since parametric tests estimate unknown parameters from the sample.

Normality lets the sampling distribution be modelled by known theoretical distributions.

Homogeneity of variance keeps group variances comparable for valid inference.

When these assumptions fail, non-parametric tests are preferred.