export type SampleStats = {
    n: number;
    mean: number;
    variance: number;
};
export declare function sampleStats(values: number[]): SampleStats;
export declare function welchT(a: SampleStats, b: SampleStats): {
    t: number;
    df: number;
} | null;
export declare function welchPTwoSided(t: number, df: number): number;
export declare function sampleNormal(mean: number, stddev: number): number;