study for exam Flashcards
what is alpha
probability of making type 1 error
what is beta
probability of making a type 2 error
bimodal distribution
frequency distribution with 2 approx. equal frequencies that are both clearly larger than others
what is a cell
used in chi-square test for independence
the particular combination of categories for 2 variables in a contingency table
chi-square statistic
stat that reflects the overall lack of fit between expected frequencies and observed frequencies
chi-square test for goodness of fit
procedure that examines how well an observed frequency distribution of a single nominal variable fits some expected pattern of frequency
chi-square test for independence
procedure that examines whether the distribution of frequencies over the categories of one nominal variable is unrelated to the distribution of frequencies over the categories of a second nominal variable
when is a chi test used
when the variables are nominal
comparison distribution
the distribution used in hypothesis testing that represents the population situation if the null hypothesis is true
comparison distribution
the distribution used in hypothesis testing that represents the population situation if the null hypothesis is true
confidence interval (CI)
range of scores that is likely to house the true population mean
correlation coefficient (r)
measure of degree of linear correlation between 2 variables
correlation coefficient range
-1 to +1
-1 being a perfect negative linear
+1 being a perfect positive linear
cramers phi
measure of effect size for chi-square test for independence used with a contingency table that is larger than 2x2
degrees of freedom
number of scores free to vary when estimating the population parameters
it is the number of scores minus the number of samples eg. single sample is n-1
dependent variable
the variable you measure
considered the effect and is dependent on the independent variable
criterion
causality
the independent variable is the cause of the dependent variables results
directional hypothesis
research hypothesis predicting a particular trend between populations eg. pop 1 has a higher mean than pop 2.
how many tails used for directional hypothesis?
1 tail t test
distribution of differences between means
distribution of differences between means of pairs of samples such that, for each pair of means, one mean is from one population and the other mean is from a second population.
(the comparison distribution in a t test for independent means)
distribution of means
distribution of means of samples of a given size from a population. (the comparison distribution when testing hypotheses involving a single sample of more than one individual)
expected frequency (E)
in a chi-square test, number of people in a category or cell expected if the null hypothesis were true
histogram
barlike graph to display frequency table data
independent variable
variable considered to be the cause
(the one you change)
(predictor)
kurtosis
the extent to which a frequency distribution deviates from a normal curve in terms of whether its curve in the middle is more peaked or flat than a normal distribution
linear correlation
relationship between 2 variables that shows up on a scatter diagram as the dots roughly following a straight line
mean
average of a group of scores
mean of a distribution of means
the mean of a distribution of means of samples of a given size from a population (it comes out to be the same as the mean of the population of individuals)
median
middle score when all scores are ranked chronologically
mode
value with the greatest frequency in a distribution
negative correlation
relation between 2 variables in which high scores in one go with low scores in the other (on a scatter diagram the dots roughly follow a straight line sloping down to the right. less than r=0.11)
95% confidence interval
95% chance that the population mean falls within the interval
99% confidence interval
99% chance that the population mean falls within the interval
no correlation
no systematic relationship between variables
r=0
nominal variable
variable with values that are categories (names rather than numbers) this is also called categorical variable
nondirectional hypothesis
research hypothesis that does not have a prediction in direction between 2 populations
observed frequency (o)
in a chi-square test, the number of individuals actually found in the study to be in the category or cell
one tail test
hypothesis-testing procedure for a directional hypothesis, situation in which the region of the comparison distribution in which the null hypothesis would be rejected is all on one side (or tail) of the distribution
phi coefficient
effect size measure for chi-square test for independence with a 2x2 contingency table
the pooled estimate of population variance
in a t-test for independent means weighted average of the estimates of the population variance from 2 samples
positive correlation
relationship between 2 variables in which both variables increase with each other, approx linear line sloping up into the right
standard deviation of a distribution of means
squared root of the variance of distribution of means
standard error of mean
standard error
standard deviation of the distributions of differences between means
in a t-test independent means, square root of the variance of the distribution of differences between means
statistical power
probability that a study will give a sig. result if the h1 is true
stat sig
conclusion that the results of a study would be unlikely if in fact the sample studied represents a pop. than no different to reg population. an outcome of hypothesis testing in which Ho is rejected
t-test
hypothesis testing procedure in which the population variance is unknown
single sample t-test
hypothesis-testing procedure in which the population variance is unknown with a single sample
dependent t-test
hypothesis-procedure in which the population variance is unknown and the 2 populations are related
independent t-test
hypothesis-procedure in which the population variance is unknown. 2 separate groups of people tested
2 tail t test
hypothesis-procedure for a nondirectional hypothesis
type 1 error
rejecting the Ho when it is true, getting a stat sig result when infact the H1 isn’t true
type 2 error
failing to reject the Ho when its false
variance
measure of how spread out a set of scores are
variance of distribution of differences between means
one of the numbers figured as part of a t-test for independent means it equals the sum of the variances of the distributions of means associated with each of the 2 samples
variance of DOM
variance of the pop divided by the number of scores in each sample
z test
hypothesis-procedure in which the population variance is known. Single sample
qualitative research
a process of naturalistic inquiry that seeks an in-depth understanding of social phenomena within their natural setting
deductive reasoning
Deductive reasoning works from the more general to the more specific
theory, hypothesis, observations, confirmation
inductive reasoning
moving from specific observations to broader generalizations and theories
observations, patterns, tentative hypothesis, theory
