Reading statistics Flashcards
What is the mean?
The average score in a set of data
What is the standard deviation?
how much scores vary on average from the mean
What does a letter mean in descriptive stats?
tells you what kind of statistical model was used
what is a t-test
a family of statistics that is used to look at differences between two groups (conditions)
The bigger the value, the bigger the difference between the two groups
What are degrees of freedom?
indicates info about sample size and possibly how many conditions are in the study (combination of the two are important to knowing if score is significant)
what is an r test?
looks at the correlation (relationship) between two variables. It is given a value between -1 and 1
What kind of tests are there?
Studies where you’re looking at the differences between two groups (t test) e.g. autisim study
Studies where you’re looking at relationships and assocations between variables (r test)
What is correlation?
The assoication between two variables
What is the correlation co-efficient?
A value given to capture the relationship between 2 variables between -1 and 1
What does a 0 correlation value mean?
weaker strengh of correlation
What does a -1 correlation co-efficient mean?
perfect negative correlation
What is a positive negative correlation?
When one variable increases, the other decreases
What does a +1 correlation mean?
perfect positive correlation
what is a positive correlation?
When the value of one variable increases (or decreases) the other increase (or decreases)
What is d?
Measure of effect size, telling you how big the effect you’ve just observed is.
It is a measure of the degree to which differences in a dependent variable are attributed to the independent variable
Anything bigger than 0.8 is a large effect.
What are the rules of thumb for r?
.1 - .3 = weak correlation
.3 - .5 = moderate correlation
.5 -1 = strong correlation
What is p?
Probability, the likelihood that an event will occur due to chance or not.
What are the values of p between?
0 and 1
What does a p value of 0 mean?
an event which is absolutely certain NOT to happen
what does a p value of 1 mean/
an event which is absolutely certain WILL happen
What does a p value of 0.5 mean?
an event which is a likely to happen as not happen
When does a p value become statistically significant?
when p< .05 , it regjects the null hypothesis (that there will not be a difference)
when does a p value vecome non-significant?
when p>.05, it is non-significant and fails to reject the null hypothesis.
what are measures of central tendency?
mean, medium, modal scores
What does dispersion around the average central tendency show?
how the scores varied
what is the problem with the p value?
doesn’t show the range of effect size
what are the purposes of inferentail statistical tests?
calculates statistical significance and allows us to draw conclusions
used to determine whether changes in a dependent variable are caused by the IV
what do descriptive statistics allow?
collecting analyzing and describing data
what is a one tailed hypothesis?
when you have specified the direction of the relationship between variables or the difference between the two conditions.
Also called a directional hypothesis. You are pointing to the answer.
What is a two tailed hypothesis?
where you have predicted that there will be a relationship between variables or a difference between the two conditions, but you have not predicted the direction of the relationship between the variables or the difference between the conditions.
Non-directional hypothesis.
What are inferential statistics?
Researchers used them to demonstrate that a change in the value of a dependent variable can be attributed to a change in the value of an independent variable, rather than the chance, random variation.
