Statistics Flashcards
Mean
Add all values together and divide by how many there are
Median
the middle value (average middle 2 if odd number of values
Mode
the most frequently observed value
Range
the range in values (maximum and minimum)
Standard deviation
estimate of the average variability (spread) of the data
95% confidence interval
the range of values around that statistics (so 95% of values will fit into between the range of values)
Standard error
Standarderrorthestandarddeviationofthesamplingdistributionofagiven statistics
P value
-the probability of falsely rejecting the null hypothesis
-The null hypothesis is that there is no difference
- P < 0.05 is described as significant.
- P < 0.05: Essentially if its less than 0.05%. Therefore, you are 99.95% sure there is a significant difference!
Normal distribution
• Important for quantitative data
• Ensures that data is representative of a “normal” population
• Helps determine how we present data
• Helps determine what statistical test we would use to analyse data
Tests for normal distribution
-Kolmogorov-Smirnov test Or Shapiro-Wilk test
What does it mean if they value is significant
it indicates the sample is NOT normally distributed
Normal distribution on SPSS
-copy data into SPSS
-click analyse
-descriptive statistics then explore
-add variables into the dependent list
-click on plots with tests,histogram an then continue
Parametric
• If our data is normally distributed we choose “PARAMETRIC” tests
Non parametric
If our data is not-normally distributed we choose “NON-PARAMETRIC” tests
Type 1 error
Occurs when we believe that there is a genuine effect in our population, when in fact there isn’t
Type 2 error
Occurs when we believe there is no effect in the population, when there is
Two tailed
= A test of a non-directional hypothesis, i.e. x may or may not predict y or x is maybe different from y
One tailed
= A test of a directional hypothesis, i.e. x will predict y or x is different from y
What is statistics
Collection,organisation,analysis,interpretation and presentation of data
How to calcite mean.mode range on SPSS
-copy data into SPSS
-analyse, descriptive statistics ,explore
-click the arrow to add variables into the dependent list
-click statistics and press ok
How to determine if ur data is paired(dependent) or unpaired(independent)
Compare participants in different group
>they are independent from each other,different people in each groups receiving different types of treatment
Compare participants in the same group
>they are dependent same people tested twice receiving the same treatment
Tip:if it has a control group it is independent
T test(2 types depending on whether your data is independent or dependant)
-independent t-test= as your data is independent from each other eg different groups
-dependent t test=as your data is dependent on each other
what type of data is t Test used for
Parametric
How do u determine if the data is parametric
Complete a Kolmogorov-Smirnov or Shapiro-wilk test to see if the p value is significant,if its not it means its normally distributed so its parametric
Levenes test for equality of variance
tests whether your groups are similar, i.e. do you have significantly more participants in one group than the other. If the p value for this is significant, choose the p value that corresponds
Degrees of freedom
Number of participants minus number of groups
T
T statistics measures the size of the difference relative to the variation in your sample data.The greater the magnitude of T,the greater the evidence against the null hypothesis
What does ANOVA tell u
That there is. A difference between groups
What doesn’t the ANOVA tell u
What group the difference is between is so we run a post-hoc tests which then compare each group to each other to work whether which Ines are different from each other
