Lecture 4 Flashcards
What is a frequency distribution?
Shows how many people got which scores
What is a histogram?
Graph of frequency distribution-frequency on Y axis. Gives general idea of score distribution.
What are the measures of central tendency?
Descriptions of what a typical score is (mean, median, mode)
What are the mean, median, and modes?
Mean: Average
Mode: Most common score
Median: Half scores are above, half are below
What are the pros of using the mean?
The most common measure of central tendency, used a ton
What are some cons of using the mean?
The average can be really swayed by extreme scores-having one high score drastically changes average
What are the pros and cons of the median?
Pros: Unaffected by extremes
Cons: Can miss important data
What happens if there are 2 modes?
If they aren’t close together, this can represent 2 different populations each with their own mode.
What are the three measures of variability?
1) Range
2) Variance
3) Standard Deviation (square root of variance)
How do you calculate variance?
1) Calculate how far each score is from the mean
2) Square scores, calculate average of squared values
3) Square root the average to get SD
What is the normal curve?
Bell shaped curve that represents the theorhetical distribution of scores in a population (like a histogram, but histogram is for a sample).
What are the areas to remember of the bell curve?
68% fall within 1 SD of the mean, 95% fall within 2.
What is one of the key properties of the normal curve?
Mean = median =mode
What is the Flynn Effect?
Steady population level increases in intelligence over time- average is always 100, but shifts to the right every few years.
What is an exception to the Flynn Effect?
OVer the past 20 years, the IQ curve has been going backwards.
