Inferential Statistics Flashcards
Data from samples are used to make inferences about what?
Populations
Researchers make what about an entire population based on smaller number of observations?
Generalization
If many different samples were taken from a population, it would produce what?
Distribution of sample means
If different samples were taken an infinite number of times it would be called what?
Sampling Distribution
What can be inferred from the sample?
Population Mean
The speed of means around the mean of a sampling distribution is called?
Standard Error of the Mean (SEm)
The standard error of the mean can be estimated from what?
Sample
SEm is higher when?
Sample SD is Large
Sample Size is Small
SEm is lower when?
SD is Small
Sample Size is Large
What type of SEm is preferred?
Smaller because it’s more precise
What is a range of values that is likely to contain the population parameter that is being estimated?
Confidence Interval (CI)
The probability that this range of values contains the population parameter is typically what?
95%
One can have a 95% confidence that the value of the true mean lies within the what?
Calculated Interval
What are the steps to calculating a CI?
- Find the Z-score
- Multiply Z-score by SEm
- Add product to sample mean to find upper limit of CI
- Subtract product from sample mean to find lower limit
What is related to the size of the sample and the size of the data variation?
Size of CI
A small sample and large variation causes what?
Larger CI
A large sample and small variable causes what?
Smaller CI
What is an assumption that appears to explain certain events, which must be tested to see whether it is true?
Hypothesis
What are the 2 types of hypothesis?
Research Hypothesis
Null Hypothesis
Hypothesis testing involves what?
Comparison of means of groups in an experiment
What is the objective of the hypothesis tests?
Find out whether they are significantly different from each other.
What will verify is the hypothesis is real?
Statistical Tests
The null hypothesis states that there is no difference between what?
Group Means
The research hypothesis is accepted only if the null hypothesis is what?
Proves to be unlikely
What is unlikely to be due to chance?
Results of a study
Statistical significance at a specified probability level is referred to as?
Alpha
Statistical significance must be at least 95% unlikely that the null hypothesis is true before what?
It can be rejected
P values must be equal to or less than 5% in order for results of a study to reach a level of what?
Statistical Significance
The level of significance is NOT the same as?
P Value
The P value is calculated at the end of the study and must be
Statistical Significance
What is it called when researchers perform a lot of statistical tests on their data?
Fishing
Fishing increases the chance that at least one of the tests will do what?
Wrongly reach statistical significance
What type of error occurs when rejecting a true null hypothesis?
Type I error
What type of error occurs with a failure to reject a false null hypothesis?
Type II error
The probability of making a type I error is equal to the value of?
Alpha
The probability of making a type II error is equal to the value of?
Beta
As alpha becomes smaller, the chance of making a type I error does what?
Decreases
What is the probability of correctly rejecting a false null hypothesis?
Power
Power depends on what?
Sample Size
Magnitude of difference between group means
Value of alpha
Power increases as sample size?
Increases
What power value is sought out by researchers?
0.80
If the value specified as the difference between group means in the null hypothesis is included in the 95% CI, then the null hypothesis should?
NOT be rejected
If 0 is not included in the 95% CI, the null hypothesis should?
be rejected
What determines the probabilities associated with relationships in studies?
Statistical Tests
What are examples of statistical tests?
T-test
ANOVA
Chi-Square
What is used to find out whether the means of the two groups are statistically different?
T-Test
T-test only indicates what?
Means are different
The t-test can be used for a single group by comparing the mean with what?
Known Values
The data of a t-test should be normal and involve what?
Interval or Ratio Measurement
What are alternative to the t-test?
Mann-Whitney U Test
Wilcoxon Test
With a paired t-test the groups are?
Dependent
ANOVA (analysis of variance) is used to compare means when more than 2 groups are involved and repeating t-test will increase the probability of?
Producing Type I error
ANOVA can only compare what?
One outcome variable
ANOVA provides information about whether there are any significant differences among the what?
Group Means
What are the assumptions of an ANOVA test?
Normally distributed data
Independent groups
Variances of groups equal
Comparison groups compare group pairs and include?
Tukey
Bonferroni
Scheffe
What test is used to test hypotheses involving categorical data?
Chi-square Test
What are the 2 versions of the chi-square test?
Chi-square goodness of fit
Chi-square test of independence
The chi-square goodness of fit is called that because it tests whether observed frequencies fit against what/
Expected Frequencies
A chi-square table is used to see if the results are?
Statistically significant
df is the number of categories minus
1
What test involves frequencies of one variable that is compared with another to see if they differ significantly?
Chi-square test of independence
What is used for a chi-square test of independence?
2x2 contingency table
