Averages And Measures Of Distribution

Question 1

Measures of distribution-

Standard deviation

Answer 1

Standard deviation

1) Find the MEAN SCORE from your set of data
2) For each score calculate: the score MINUS the mean
3) SQUARE these numbers
4) ADD the squared numbers together
5) DIVIDE that number by n-1 (n=number of participants)
6) Find the SQUARE ROOT of that number

Question 2

Types of Data and averages

Answer 2

For INTERVAL data- find the MEAN
For ORDINAL data- find the MEDIAN
For NOMINAL data- find the MODE

Question 3

Calculated value

Answer 3

Mann-Whitney U test calls it- U
Wilcoxon calls it-T
Chi squared calls it- CHI SQUARED or X2
Spearman’s Rho calls it- RHO or r

Question 4

Probability Level

Answer 4

P= probability and expresses how unlikely the results have to be before you will treat them as a pattern
P<0.05= means the probability that random variations are at work is equal to or less than 0.05/5%
Percentages=
0.5=50% 0.1=10% 0.05=5%

Question 5

Probability Level 2

Answer 5

P<0.5 -
This is a 50% chance the results are down to RANDOM VARIATION. Doesn’t prove anything- almost the same as dumb luck

P<0.1 -
This is a 10% chance the results are down to RANDOM VARIATION. Still doesn’t prove much, wouldn’t put trust in a study only 90% likely to be accurate

P<0.05 -
This is a 5% chance the results are down to RANDOM VARIATION. Not great but ‘good enough’- used for classroom research. Professional researcher usually aim for something better

P<0.01 -
This is a 1%chance that the results are down to random variation, pretty impressive

P<0.001 -
Only 0.001% chance that the results are down to random variations. Kind manufacturers use when declaring products ‘safe’ for the public- unlikely to damage you. Refuting null hypothesis at this level= discovered a STRIKING PATTERN OR TREND= 99.9% likely to be true- need large sample