Evidence Based Practice - Week 12

Flashcards on statistical tests

Null Hypothesis (H0)

Treatment B is no more effective than treatment A for this condition.

Alternative Hypothesis (HA)

Treatment B is more effective than treatment A for this condition.

Null Hypothesis

Fundamental world view of statistical tests is as follows: “Nothing is different – any observed differences are just random error.”

Statistical Tests

Report on the probability of the null hypothesis being true.

Standard Error of the Mean (SEM)

Calculated by: SD / sqrt(n)

95% Confidence Interval (CI) Overlap

If the 95% CIs of two groups means overlap then we can say Statistically that there is no difference between the groups

Alpha (α)

Also known as the level of significance; represents the probability of obtaining results due to chance (conventionally 0.05); also represents the chance of making a Type I Error.

Type I Error

The chance that you reject the null hypothesis when in reality you should fail to reject the null hypothesis. In other words, your sample data indicates that there is a difference when in reality, there is not (false positive).

95% Confidence Interval (CI)

The range within which we are 95% certain that the true population treatment effect will lie.

Statistical Significance

If the CI for a mean difference does not include 0, then a statistically significant difference between the groups has been shown.

P-value

The probability that the observed difference between 2 groups might have occurred by chance.

Statistical Significance (p < 0.05)

The observed difference between the groups is so unlikely to have occurred by chance that we reject the null hypothesis and accept the alternative hypothesis that there is a real difference between the treatment groups.

Minimal Clinically Important Difference (MCID)

Smallest amount thought to be worthwhile – for the client.

Minimal Detectable Change (MDC)

A statistical estimate of the smallest amount of change that can be detected by a measure that corresponds to a noticeable change in ability.

Generalisability

Clients similar? – are they like the people I treat? Treatment applied appropriately? – can / would I do that? Outcome useful? – is it what the client wants? Effect size meaningful? – worth the time, money, risk?