Estimation and confidence, significance test and p values Flashcards Preview

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Flashcards in Estimation and confidence, significance test and p values Deck (10)
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1

How to deal with uncertainty

confidence interval, statistical significance test (if testing hypothesis)

2

What is standard error of mean and what does it do

standard deviation of sample means, provide estimate of precision of sample mean. SD/squareroot of n. If SE decreases, precision greater for larger samples

3

How to work out confidence interval

mean-multiplier*Standard error of mean to mean+multiplier*Standard error of mean
Multiplier=1.64 for 90% CI, 1.96 for 95% Ci, 2.58 for 99% CI

4

Standard error of proportion, how calculated and when used

squareroot (p(1-p)/n), large sample size

5

95% confidencce interval for a proportion from large sample

p-1.96standard error of proportion to p+1.96*standard error of proportion

6

What is classified as a large sample

Mean: sample size of 100 is considered large of sample mean
Proportions: for sample proportion, sample size considered large if r and n-r are both greater than 5. If not, binomial confidence interval can be calculated

7

2 tailed and 1 tailed test

2-alternative hypothesis is general and allows the difference to be in either direction
1-doesn't distinguish between no difference and harmful effect.
2 sided tests should always be used unless justification

8

Error in significance testing

type 1: getting a significant result in sample when null hypothesis is in the underlying population (false significant)
type 2-getting a non significant result in sample when null hypothesis is false in the underlying population

9

What is statistical significance (p value) influenced by

size of real effect in population sampled, smaple size, variability of measure involved

10

Does statistical significance always link to clinical significancee

no