Statistics primer

Question 1

What happens when we compare larger samples?

Answer 1

We are more likely to obtain a statistically significant result

Question 2

What is the value of p dependant on?

Answer 2

• sample size
• type of test being used
• size of the effect we are studying

Question 3

What p value is used as the standard?

Answer 3

0.05
- less than means that the result was statistically significant
- less than 0.01 means that the data was highly statistically significant

Question 4

Why do many scientists not consider the p value to be significant? And what do they use instead

Answer 4

Because they consider it to be conservation. They favour the retention of the null hypothesis instead to not make Type 1 errors

Question 5

What is class interval?

Answer 5

the range of values assigned to a group of data points

Question 6

Characteristics of a normal distribution curve

Answer 6

• it is symmetrical about the mid point of the horizontal axis
• The mean, median and mode all fall at the point at which it is symmetrical
• The ‘asymptotes’ (tail ends) of the perfect curve never quite meet the horizontal axis. Although
  for distributions of real large samples there are existing real limits, we can always hypothesise a
  more extreme value in a theoretical population.
• It is known what area under the curve is contained between the central point (mean) and the
  point where one standard deviation falls. In fact, working in units of one
  standard deviation, we can calculate any area under the curve.

Question 7

What are z scores a type of?

Answer 7

A particular kind of standing score

Question 8

What is a normal distribution curve?

Answer 8

the bell shaped curve that represents real valued random variables where the distribution isn’t known

Question 9

What is a z score

Answer 9

the number of standard deviations a score is from the mean.

Question 10

What is the formula for z score

Answer 10

z = x - x^- / s,
where s is the standard deviation and x - x^- is the deviation score

Question 11

What is standard deviation?

Answer 11

a measure of how spread out the values in a dataset are from the average (or mean) value

Question 12

What are the values of standard distribution percentage on the normal curve?

Answer 12

1 s.d = 34%
2 s.d = 13.5%
3 s.d = 2.35%
4 s.d = 0.15%