Statistics Flashcards
when is the median used?
ranked or skewed data
when is the mean used?
interval level data
how to calculate variance
square the arrows, add squares, divide by total number of arrows
standard deviation
take sq root of variance figure
what is variance used for?
to tell us what the spread of the data is
what is the standard deviation?
a measure of the spread of the data
measures of central tendency
mean, median, mode
in giving descriptives, what should we report?
the mean and the standard deviation
what does the standard deviation show?
the variance within the data
what is the null hypothesis
a statement that there is no effect
what is the significance?
the chance of finding effect
what is a statistical effect for?
it tells us the probability that an effect occurred by chance
what significance level should we look for?
.05
what is a test distribution?
the distribution of the scores, most fall in the centre 95%, with 2.5% either side (bell curve shape)
what is a critical value?
the value a test must reach for significance (the number you compare your ‘absolute value’ to)
if a result is p < .05 is this significant?
yes
what is the p value?
the measure of probability that the hypothesis being correct was chance (you want it to be below .05 to be significant - 5%)
if p < .001 what does this mean?
that it was very significant
if p > 0.05 what does this mean?
it was not significant
what are degrees of freedom?
the number of values that are free to vary
what is the most common constraint giving N-1?
the mean of the scores (as this is fixed)
are degrees of value better in small or large samples?
in small they’re better, because in large the critical values are usually similar
the higher the df, the lower the…
critical values are.
because you tend to have more people, (so N-1 is higher) so it’s easier to find affect and reach significance because there is more data
the smaller the p value, the higher the…
critical values are.
more significant; therefore values are higher to reach.
