Understanding Statistics Flashcards
Descriptive Statistics
summarizes data so they an easily be understood
frequency distribution
how data is distributed
frequencies
example of descriptive statistic
percentages
describe how many per hundred
sampling errors
possibility that a sample does not accurately reflect the population
Inferential statistics
help researchers make generalizations about the characteristics of populations from the study
margin of error
inferential statistic estimating possible sample error
significance tests
- family of inferential statistics which help decide whether differences in descriptive statistics are reliable
- determine the probability that the null hypothesis is true
parameters
values from a census
statistics
for values from studies in which samples were examined
samples yield…
statistics
populations yield…
parameters
Null hypothesis
the observed difference was created by sampling error
probability symbol
p
statistically significant
when the researcher rejects the null hypothesis
Scales of Measurement
- Nominal
- Ordinal
- Interva
- Ratio
Nominal
- naming
2. words
Ordinal
- ordering
2. ranking
Interval
- measures the amount of difference
- equal distance between
- no absolute zero
Ratio
- equal interval
2. absolute zero
Frequencies symbol
f
number of cases symbol
N
univariate analysis
analyzing how participants vary on only one variable
bivariate analysis
relationship between two nominal variables
chi-square
- usual test of the null hypothesis for differences between frequencies
- x2
degrees of freedom
- df
2. not descriptive statistics
Type I Error
rejecting the null hypothesis when it is in fact a correct hypothesis
Type II Error
failing to reject the null hypothesis when it is in fact an incorrect hypothesis
Frequency Polygon
using data from a frequency distribution to construct a graph
Normal curve
smooth, bell-shaped curve
skewed distributions
a distribution that has a tail to one side
positive skew
tail to the right
negative skew
tail to the left
mean
- balance point in a distribution
2. average calculation
median
- middle score
mode
most frequently occurring score
synonym of averages
measures of central tendency
Standard deviation
- S or SD
2. variability
variability
amount by which participants differ from each other
range
highest score minus the lowest score
Pearson Correlation Coefficient
- most widely used coefficient
- r
- Pearson r
direct relationship
- positive relationship
2. both variables are either high or low
inverse relationship
- negative relationship
2. one variable is high and one variable is low
coefficient of determination
- r2
2. needed to represent correlation in perms of percentages
t test
used to test the null hypothesis regarding the observed difference between two means
ANOVA
analysis of variance
one-way ANOVA
single-factor ANOVA
Five Considerations in Practical Significance
- cost-benefit analysis
- crucial difference
- client acceptability
- public and political acceptability
- ethical and legal implications