test 4 one way randomized anova Flashcards
Researches may choose to use a design with an more than two levels for what three reasons?
- the can compare multiple treatments
- they can compare multiple treatments with no treatment
- the can compare placebo group with control and experimental groups.
Using 3 different experiments to compare 3 levels will increase what type of error?
Type 1 error rate
means we reject the null when we should have failed to reject it
What would the type one error be for an experiment with 3 levels and an alpha of .05?
1-(1-a)^c a=alpha, c=number of levels 1-(1-.05)^3 1-(1.05)^3 1-.95^3 1-.86 =.14 so, the probability of a type one error on atleast one of the three tests is 14%
One way of counteracting the increased chance of a type 1 error is to use a more stringent alpha level. The _________, in which the desired alpha level is divided by the number of test or comparisons, is typically used to accomplish this.
Bonferroni adjustment
What would the Bonferroni adjustment be for a test with 3 levels and an alpha of .05?
.017
A more stringent alpha decreases the _______ and increases the ________.
decreases the Type I error and increases the Type II error.
A better method for comparing 3 levels or more is to use _______ to compare all groups rather than doing 3 experiments.
a single statistical test - the ANOVA (analysis of variance)
A placebo group allows for a more accurate assessment of a therapy’s effectiveness because, in addition to spontaneous remission, it controls for _________.
participation expectation effects
Imagine that a researcher wants to compare four different types of treatment. the researcher decided to conduct 6 different studies to make these comparisons. What is the probability of a Type I error, with alpha = .05? Use the Bonferroni adjustment to determine the suggested alpha.
1-(1-a)^c a=alpha, c=number of levels 1-(1-.05)^6 1-.95^6 1-.735 .26.5 26.5%
The Bonferroni adjustment would be .008 for each level.
(.05/6) = .008
An inferential statistical test for comparing the means of three or more groups.
ANOVA
______ subjects design has different participants in each group.
______ subjects design has the same people in each group.
between = different ppl within = same ppl
When the design is a between-subjects design, we use a __________ statistical test.
one-way randomized ANOVA
An inferential statistical test for comparing the means of three or more groups using a between-subjects design and one independent variable.
one-way randomized ANOVA
The term “one-way” indicated that the design uses _____.
only one independent variable
The term “randomized” indicates that participants are ______.
randomly assigned to conditions in a between-subjects design.
The null hypothesis for an ANOVA is that the sample means represent _______.
the same population
Ho: µ1 = µ2 = µ3
The alternative hypothesis of an ANOVA is that the sample means represent ______.
different populations
Ha: at least one µ ≠ another µ
The mean performance across all participants in a study is the ________.
grand mean
The amount of variability among the scores cased by chance or uncontrolled variables.
error variance
We are interested in whether the variability of means is due primarily to the IV, or to _______.
error variance
The error variance can be estimated by looking at the amount of variability _____ each condition.
within
The variance within each condition; an estimate of the population error variance.
within-group variance
An estimate of the effect of the independent variable and error variance.
between-groups variance
The systematic variance between the groups could be due to the _______ or to the _______.
the effects of the Independent variable (variance due to the experimental manipulation) or due to the influence of uncontrolled confounding variables (variance due to extraneous variables).
The ration of between-groups variance to within-groups variance.
F-ratio