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Questions and Answers
What is the term for failing to reject the null hypothesis when it is false?
What is the term for failing to reject the null hypothesis when it is false?
What happens when alpha is greater than 0.05?
What happens when alpha is greater than 0.05?
What is the consequence of setting alpha at 0.01?
What is the consequence of setting alpha at 0.01?
What is the term for rejecting the null hypothesis when it is true in the underlying population?
What is the term for rejecting the null hypothesis when it is true in the underlying population?
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What is the effect of decreasing alpha?
What is the effect of decreasing alpha?
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What is the relationship between alpha and type I errors?
What is the relationship between alpha and type I errors?
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What is the consequence of setting alpha at 0.10?
What is the consequence of setting alpha at 0.10?
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What is the term for the probability of rejecting the null hypothesis when it is true?
What is the term for the probability of rejecting the null hypothesis when it is true?
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What is the effect of increasing alpha?
What is the effect of increasing alpha?
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What is the consequence of setting alpha at 0.01?
What is the consequence of setting alpha at 0.01?
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Study Notes
Research Methods
- There are two main methods of research: deduction and induction
- Deduction: general theory to particular data
- Induction: particular data to a general theory
Measurement Scales
- There are four types of measurement scales:
- Nominal: categorical data with no order or equal intervals
- Ordinal: categorical data with order, but no equal intervals
- Interval: distances between each interval on the scale are equal
- Ratio: equal intervals with a true zero point
Theory and Hypothesis
- Theory: an explanation or set of principles that is well substantiated by repeated testing and explains a broad phenomenon
- Hypothesis: a specific prediction made by a theory
Analyzing Data
- Descriptive statistics: methods for summarizing and describing data
- Frequency distribution/histogram: a graph plotting values of observations on the horizontal axis, with a bar showing how many times each value occurred in the data set
- Stem and leaf plots: similar to histograms, but the frequency of occurrence of a particular score is represented by repeatedly writing the particular score itself
- Box and whisker plots: enable us to easily identify extreme scores and see how the scores in a sample are distributed
- Scattergram: gives a graphical representation of the relationship between two variables
Normal Distribution
- A symmetric distribution where most of the observations cluster around the central peak
- Can be used to analyze data by transforming scores to standard normal scores
Dispersion
- The extent to which a distribution is stretched or squeezed
- Quartiles: three values that split the sorted data into four equal parts
- Lower quartile: median of the lower half of the data
- Upper quartile: median of the upper half of the data
- Interquartile: difference between the upper and lower quartile
Confidence Intervals
- Point estimate: a single figure estimate of an unknown number
- Interval estimate: a range within which we think the unknown number will fall
- Standard error: the deviation of a sample mean from the actual mean of a population
Errors in Hypothesis Testing
- Type I error: rejecting the null hypothesis when it is true
- Type II error: failing to reject the null hypothesis when it is false
- Alpha (α): the probability of a type I error
- Beta (β): the probability of a type II error
- The larger the sample size, the lower the sampling error
One-Tailed and Two-Tailed Tests
- One-tailed test: tests a directional hypothesis (e.g. "there is a significant increase in...")
- Two-tailed test: tests a non-directional hypothesis (e.g. "there is a significant difference in...")
Setting Alpha at 0.05
- If alpha > 0.05, then we are more prone to type I errors
- If alpha < 0.05, then we are more prone to type II errors
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Description
This quiz covers two main methods of research, including deduction and induction, and statistical concepts like interval scales. It also includes ranking students based on their grades.
