Significance

Question 1

Magnitude of estimate: Signal

Answer 1

“central tendency” in what we are interested

ex after 4 weeks, pts recieving tx A had a mean improvement of 25 deg AROM

Signal=25 deg AROM

Often expressed as change score (M2-M1)

Question 2

Magnitude of estimate: Noise

Answer 2

“dispersion”

Fluctuation associated with signal

Often expressed as variance or SD

ex For pts receiving tx A, the dispersion in improvement for AROM was 50 deg

Noise=50 deg

Question 3

Magnitude of estimate

Answer 3

Determining mag from signal/noise ratio. A way to determine magnitude by comparing Ct to dispersion.

Large the ratio, larger the difference (more important)

Smaller the ratio, smaller the difference (less important)

Ex 25 degimprovement in AROM and 50 deg SD in AROM (Signal to noise ratio = 0.5)

Question 4

Effect size

Answer 4

Mag of estimate for continuous measures

Estimates how clinical important it is

Specific type of signal to noise ratio

ES= (M1-M2) / Pooled SD

Question 5

Effect size interpretation

Answer 5

Large effect: 0.8

Moderate effect= 0.5

Small effect= 0.2

ES gives clinical relevance not p value. Wants small p value and high ES

Question 6

Interpretation of statistical significance and magnitude of estimate

Answer 6

statistical significance- probability the null is true

Mag of estimate- importance or relevance of the finding