Population + Normal distribution

Question 1

Median

Answer 1

n+1/2 if even. Middle value if odd

Question 2

Descriptive tests

Answer 2

Median , IQR

Question 3

Statistical tests

Answer 3

SD, mean, SE

Question 4

IQR range

Answer 4

75%-25% i = 0.25(n+1)

Question 5

Spread

Answer 5

Distribution of data = IQR and range

Question 6

Location

Answer 6

Mean and median

Question 7

5 figure summary and how is it displayed

Answer 7

Median, Range (Max/min). Upper quartile, Lower quartile. Box and whisker plot

Question 8

Histograms

Answer 8

Display distribution of data, large samples and appropriate bin size make this easier

Question 9

u and sigma (o)

Answer 9

u = population mean, o = population SD

Question 10

Qualitative vs Quantitative data

Answer 10

Qualitative = categorical
Quantitative = numerical data - continuous

Question 11

Normal distribution

Answer 11

Bell shaped curve - symmetrical equal populations located same distance away from mean
Peak located at u, width determined by sigma

Question 12

Mean

Answer 12

Average m = x1+x2+x3/n

Question 13

Standard deviation

Answer 13

Deviation around mean s = SD
Sum of each value ((x) - mean)2 ( squared to remove - then square rooted to remove square. Divide sum of the mean by n-1
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Question 14

AUC

Answer 14

Always =1

Question 15

x=u + zo (sigma)

Answer 15

P depends on the value of z. For given values of z allows the visualisation of the values that differ by a set SD from the mean

Question 16

1SD

Answer 16

P = 0.84, 2P-1 = 0.68

Question 17

Cumulative probability

Answer 17

Value of P for a given value of X

Question 18

2SD

Answer 18

P = 0.977, 2P-1 = 0.954

Question 19

1.96 SD

Answer 19

0.95

Question 20

UP/Lq

Answer 20

u +/- 0.675o

Question 21

Importance of normal distribution

Answer 21

Arises empirically - statistical test assume/require normally distributed data.
Variables normally distributed due to biological mechanisms

Question 22

Rapid screen of normality

Answer 22

2. 5% of population below u-2o

16. 5% population below u-o

Question 23

Distribution free methods

Answer 23

Don’t require statistical tests - Assumption of normality isn’t critical. At best hypothesis tests and cannot cope with anything but the simplest structure

Question 24

Best way to assess normality

Answer 24

Probability plot. Large samples clustering of data around u, largest and smallest will symmetrically vary around u by o

Question 25

3 SD

Answer 25

99.7%

Question 26

Outliers effect on median and mean

Answer 26

Mean often skewed by outliers. Median more resistant may be a better descriptor