1. Understanding Results
Describes a data set
Descriptive Statistics
What does sample tell us about the population (generalization)?
Inferential Statistics
Measures of central tendency: mean, median, mode, variance (standard deviation)
Descriptive stats simply describe a data set. Frequency charts such as bar graphs, line graphs, and pie charts are part of descriptive statistics. They’re a way to visualize your data set.
Inferential statistics involve probability values. What is the probability that our results indicate true, significant differences between our experimental and control group, for instance? Scientists set a probability (called a p value) of .05 or less as the cut-off for statistical significance. If a p value is less than .05, it means there’s less than a 5% chance that our results are a fluke. There’s a 95% chance that we’d see the same result again with a different sample. Stated another way, 95 times out of 100, we would expect to see the same differences between groups.

2. Descriptive Statistics
Mean
Median
Mode
If two numbers are in the middle, average them to get the median.

3. Descriptive Statistics
Skew (Lopsided Distribution)
**The mean is the measure of central tendency most affected by extreme scores.**

4. Descriptive Statistics
Range: difference between the largest and smallest scores.
Descriptive Statistics
Standard Deviation: measure of how much scores vary around the mean.
Low SD = low variability
Measures of Variability
To calculate the standard deviation:
Work out the Mean (the simple average of the numbers)
Then for each number: subtract the Mean and square the result.
Then work out the mean of those squared differences.
Take the square root of the mean.

5. Wechsler Adult Intelligence Scale (WAIS)

6. The t test (Student’s T Test): statistically compares two MEANS
Every t value is associated with a p value, which is the likelihood that your results are due to chance.
The goal of most researchers is to obtain a p value of or less.
Inferential Statistics Allows you to see whether your results are due to chance.

7. Ethics

8. Ethics
An Institutional Review Board (IRB) was established in the s to evaluate all psychological research for possible moral, ethical, and legal problems.
Must have informed consent form before the study begins
Free to leave at any time; voluntary participation.
Beneficence (“Do not harm”).
Justice (subject cannot be exploited).
Must be “debriefed” after it’s over.
Deception can still be used.
The Tuskegee Syphilis Study was what prompted the creation of the IRB. People wanted to make researchers more accountable and ensure that unethical studies couldn’t happen again.
Debriefing--told what the experiment was about; have questions answered after study is over

9. Discuss…Is it ethical to…
Give people false feedback (e.g., “You’re unintelligent”) in order to study the effects of that feedback on self-esteem?
Tell someone that his response to a video indicates that he has aggressive tendencies?
Measure pain by placing heavier and heavier weights on someone’s fingers to see how much she can tolerate?