1.4 Predictions + Descriptive Statistics Flashcards
1
Q
descriptive statistics
A
are used to summarise a collection of data
2
Q
mode
A
- most common score
- advantage: real scores that actually do occur
- dis: depend on how you group the data (e.g. cancers grouped = mode way to die, individually it’s road accidents)
3
Q
median
A
- middle score (or even = avg of middle 2)
- advantage: not disproportionately affected by outliers, most efficient for estimating population means
4
Q
mean
A
- balance point of distribution of scores
- advantage: best measure for estimating a population mean from a sample
- dis: usually not real scores, easily affected by extreme values
5
Q
positive skew
A
mode –> median –> mean
_-‘’—___
6
Q
negative skew
A
mean –> median –> mode
___—’’‘-_
7
Q
deviation scores will always add up to…
A
zero
8
Q
TO GET VARIANCE
A
- figure out deviation scores
- square all the dev scores
- take the sum of all squared deviation scores
- divide by number of scores
- take the square root of this number
–TA-DAAAA–
9
Q
experimental hypothesis
A
- prediction of what will happen in your study
- should be derived either from previous findings/literature, or from a theory
- must know which kind of result will prove and which will disprove your theory
10
Q
null hypothesis
A
- idea that there is no relationship in the population and the relationship in the sample reflects only sampling error
- helps combat only testing/drawing conclusions on what we already believe
- if we reject the null hypothesis, we are saying that we have evidence of an effect not due to chance