Chapter #11 Flashcards
A normal curve is a?
theoretical frequency distribution of all possible values in a population.
In a normal distribution curve, the mode, median, and mean?
Are equal.
Levels of significance and probability are based on?
The logic of the normal curve.
In research, the probability that any data score will be within a certain range of a mean value is calculated based on?
The theory of the normal curve.
The normal curve is the frequency distribution of?
all possible population values. It is theoretical in that no naturally occurring population perfectly fits the curve. However, for a data set of 30 or more values, most distributions approximate the normal curve—a few small values, many values in the middle, and a few large values.
For a normal curve, about____are within one standard deviation of the mean, and about_________
68% of variable values
95% of the values are within two standard deviations of the mean.
Type I (more serious) and Type II (less serious) errors: Type 1 error
occurs when the null hypothesis is rejected when it is true. (e.g., when the results indicate that there is a significant difference, when reality there is not)
Type I (more serious) and Type II (less serious) errors: Type 2 error
occurs when the null hypothesis is regarded as true but is in fact false (e.g., The results indicate there is no significant difference, when in reality there is a difference)
The risk of a type II error can be determined using?
power analysis (1-β)
4 parameters of a power analysis:
- The level of significance (α = 0.05)
- Sample size
- Power (minimum acceptable power is 80%)
- Effect size (> 0.50)
Power is the probability that a statistical test will detect?
detect a significant difference if one exists (The probability of correctly rejecting H0= 1-β (power)
Descriptive Statistics: Frequency
Ungrouped frequency distributions. Grouped frequency distributions. Percentage distributions
