Interpreting Data

Question 1

what is the median?

8,4,2,11,8,3,7

Answer 1

7

Question 2

what is the mode?

8,4,2,11,8,3,7

Answer 2

8

Question 3

what is the mean?

8,4,2,11,8,3,7

Answer 3

43/7 = 6.1

Question 4

how do you calculate the standard deviation?

Answer 4

distance from the mean, squared

average squared distance from mean and then square root

Question 5

what is the standard deviation?

8,4,2,11,8,3,7

Answer 5

3

Question 6

how do you calculate the interquartile range?

Answer 6

25th to 75th centile

Question 7

what is the interquartile range?

8,4,2,11,8,3,7

Answer 7

25th centile: 3

75th centile: 8

Question 8

1, 2, 3, 4, 100

median or mean?

Answer 8

median

to avoid the influence of outliers

Question 9

what is gaussian distribution and what is it determined by?

Answer 9

bell shaped curve/ normal distribution

the gaussian distribution is determined only by the mean and standard deviation

Question 10

what happens to the gaussian distribution when there is an increase/ decrease in mean?

Answer 10

the curve shifts to the left if there is a decrease in mean

the curve shifts to the right if there is an increase in mean

Question 11

what happens to the gaussian distribution when there is an increase/ decrease in standard deviation?

Answer 11

a decrease in standard deviation causes the curve to become narrow and taller
an increase in standard deviation causes the curve to become shorter and wider

Question 12

what does 1 SD either side of the mean equal?

Answer 12

68%

the rest outlying equals to 16%

Question 13

what does 1.64 SD either side of the mean equal to?

Answer 13

90%

the rest outlying equals to 5%

Question 14

what does 1.96 SD either side of the mean equal to?

Answer 14

95%

the rest outlying equals 2.5%

Question 15

How do you calculate the 95% range?

Answer 15

mean +/- 1.96 x standard deviation

Question 16

How do you calculate the 90% range?

Answer 16

mean +/- 1.64 x standard deviation

Question 17

How do you calculate the 99% range?

Answer 17

mean +/- 2.58 x standard deviation

Question 18

what is the standard error?

Answer 18

this is the stander deviation of the means from all potential samples of the same size

Question 19

how do you calculate the standard error?

Answer 19

standard deviation / square root of the sample size

Question 20

what is the 95% confidence interval?

Answer 20

the 95% confidence interval of a sample mean contains the population mean with a probability of 95%
95% sure that the population mean is between that interval

Question 21

how do you calculate the 95% confidence interval?

Answer 21

mean +/- 1.96 x standard error

Question 22

what is the difference between standard deviation and standard error?

Answer 22

use standard deviation for the range

use standard error for confidence intervals

Question 23

does an increase in sample size affect the range or confidence interval?

Answer 23

confidence interval

sample size is used to calculate the standard error

Question 24

what does a correlation coefficient of 0 indicate?

Answer 24

there is no pattern

Question 25

what does a correlation coefficient of 1 indicate?

Answer 25

straight line

Question 26

what does a correlation coefficient of -1 indicate?

Answer 26

straight line | but for a high value for x there's a low value for y (vice versa)

Question 27

what is linear regression?

Answer 27

the linear regression line has an equation y = a + bx y os the outcome variable. x is te predictor variable. a is the y intercept. b is how steep the slope is. change in y variable divided by change in x variable.

Question 28

what is a p value for a result?

Answer 28

the probability of observing a result as or more extreme than the sample result if the underlying assumption in the population is true

Question 29

what does a p value < 0.05 indicate?

Answer 29

statistical significane | probably not a chance effect

Question 30

what a p value > 0.05 indicate?

Answer 30

not statistically significant | cannot rule out chance effect

Question 31

when can p values be calculated?

Answer 31

when there is a comparison comparing the means of 2 groups association: are the observed results different from those expected regression

Question 32

what test uses p values?

Answer 32

chi-squared test | produce test statistics which can be interpreted using p-values.

Question 33

what is the relationship between p values and confidence intervals?

Answer 33

they are consistent | if the 95% confidence interval for a difference in means does not include 0, then p<0.01

Question 34

what test is used to compare the means?

Answer 34

two sample t-test

Question 35

what does statistical significance mean?

Answer 35

the probability that an effect is not due to just chance alone