Correlation (Pearson’s r)
What does r = 1 represent in a Pearson’s correlation?
Perfect positive correlation.
What statistic is used to measure variability in data?
Standard deviation.
What does a p value below 0.05 indicate?
The result is statistically significant.
What is the difference between ratio and interval data
Ratio = 0 means 0
interval = below 0
What are parametric data characteristics
- normally distributed
- large sample size
- interval/ratio data
What does r = 0 indicate?
No correlation.
If a group has a small standard deviation, what does this mean?
The data has low variability.
If error bars overlap, what does this suggest?
The result is likely not statistically significant.
What is qualitative data vs quantitative data
Qualitative data = words
Quantitative data= numbers
What is classed as a small sample size?
20 or less
What does r = –1 represent?
Perfect negative correlation.
When looking at a graph what characteristic of the graph tells you about variability?
The size of error bars
When do you reject the Null hypothesis?
If the data indicates statistical significance
Why is the mean often used as a measure of central tendency?
Because the data is numerical (interval or ratio data).
A psychologist wants to test whether listening to music improves memory recall.
They use a large sample of 100 participants and divide them into two independent groups. One group completes a memory test while listening to music, and the other group completes the same test in silence. The scores from the two groups are then compared.
Which statistical test is suitable?
unpaired T test
If r = 0.78, what type of relationship does this show?
Strong positive correlation.
Condition 1: 1.457
Condition 2: 3.758
Condition 1 has a SD of 1.457 which shows it has lower variability WHEREAS condition 2 has a SD of 3.758
If error bars do not overlap, what does this suggest?
The result is likely statistically significant.
What would be showing in data if the best central measure of tendency was median
The data has a sequence but irregular gaps between levels
A psychologist wants to test whether drinking water improves concentration. They use a small sample of 10 participants in a repeated measures design. Each participant completes one concentration test without drinking water and then completes a second concentration test after drinking water. The results from the same participants are then compared.
Identify two (2) characteristics of the data that make it appropriate to use a Mann-Whitney U test
10 participants & repeated measures
If r = 0.98, how would you describe the relationship?
A strong positive relationship that is nearly perfect
What does variability mean?
Variability in statistics measures how spread out, dispersed, or scattered data points are within a dataset. It indicates how much scores differ from each other and the mean.
When results are not statistically significant, which hypothesis is supported?
Null hypothesis
Sushi obviously
Draw the table for choosing the type of inferential test that Miss Cochrane wants you to remember
Check work