RM 2/2 Flashcards
What does quantitative mean?
To do with numbers
What does qualitative mean?
To do with text
What is a control condition?
A condition that helps us understand the role of the IV and DV or rule out alternate explanations for results
What is matched pairs experimental design?
participants are matched between the two (or more) conditions to account for individual differences
What is an extraneous variable?
A variable not controlled in the experiment that could affect the DV
What is a confounding variable?
A type of extraneous variable that varies with the IV to influence the DV
What are the two main data types?
Categorical and numerical
What are the two types of categorical data?
nominal and ordinal
What are the two types of numerical data?
interval and ratio
What is the purpose of inferential statistics?
To compare two data sets
What is the central tendency of a normal distribution?
The vertical line from the peak to the x-axis
What is the variability of a normal distribution?
The horizontal line across the x-axis showing the spread of scores
Why is it not possible to measure all the people in a population when conducting an experiment?
time consuming
expensive
geographically challenging
What is sampling error?
Where the mean of the sample is different to that of the population
How do you work out the sample error?
sample mean - population mean
How can you lower the sampling error?
take an average across multiple samples as it will be closer to the population mean
Why are larger sample sizes better?
better estimates of the population mean
What is a confidence interval?
95% chance the population mean lies within this interval
What is variance?
A measure of dispersion
How do you calculate variance?
- difference between each score and the mean (x-x̅)
- square it (x-x̅) ²
- add all the squared differences together (Σ)
- divide by the sample size -1 (n-1)
How do you calculate standard deviation?
√Variance
How do you calculate standard error?
standard deviation ÷ √n-1
How do you calculate confidence intervals?
sample mean ± (1.96 x SE)
+ = upper 95% CI
- = lower 95% CI
What is a hypothesis?
The effect of an IV on DV
What is a false positive?
Finding an effect where there isn’t one
What is a false negative?
Not finding an effect where there is one
What are inferential statistics?
The probability your results would be replicated if the null hypothesis was true
What is a p-value?
The probability of getting your results by chance
What is the p-value in psychology?
0.05 (5%)
What is a significant and non-significant p-value in psychology?
p < 0.05 = significant
p > 0.05 = non-significant
What is the most common test of normality?
Shapiro-Wilk test
