# STATS: 2 samp Flashcards

when every # in the interval is larger than 0 that means…

there was change (no change would be 0)

Interval –>

PANIC

Test –>

PHANTOMS

POI statement (for BOTH):

The POI is the true DIFFERENCE in (means/proportions) between group 1 and group 2.

Assumptions for proportions

-random sample (for both groups)

-10% condition (for both groups)

-n1(p1) n1(q1) ~ n2(p2) n2(q2) ~ greater than equal to 10 (for approx. normal)

*use p-hat for proportion-tests*

2-Prop Z Int

define z* and interval

Conclusion for 2 sample INTERVALS

We are __% confident that the true DIFFERENCE in (proportions/means) between group 1 and group 2 is between __ and __.

Assumptions for means

-random sample (for both groups)

-10% condition (for both groups)

-for approx normal:

~both populations are normal

~n greater than or equal to 30 (CLT)

~graph: no strong skew or potential outliers for both data sets

2-Samp T Int

define t* and interval

2-Samp T Test

define t-value and p-value

2-Prop Z Test

define z-value and p-value

ALWAYS STATE YOUR …

SIGNIFICANCE LEVEL (for tests)

p-value < significance level

reject H0, stat. sig –> we DO have convincing evidence

p-value not< significance level

fail to reject H0, not stat. sig –> we DO NOT have convincing evidence

Conclusion for 2-sample tests

We do/do not have convincing evidence of a different (average/proportion) of ____ between group 1 and group 2