Chapter 16 Pwpt Flashcards by Briana Rodriguez

Measurement is?

Assignment of a number

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The nature of the variable or event determines the _________ ______ _________?

Level of measurement

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The level of measurement determines the ______ __ _________

Type of statistics

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The four levels of measurement are?

Nominal
Ordinal
Interval
Ration

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Nominal is?

Classification of variables
Lowest level
Least amount of manipulation
Dichotnomous and categorical

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Dichotonomous and categorical mean?

Dichotonomous= only 2 true variables 
Categorical= more than 2

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Ordinal? And examples?

Rankings of high or low

Frequencies, percentages, medians, percentile, rank order

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Interval? And examples?

Rankings with equal intervals between allows more manipulation
Ex. Likert, quality of life, depression, functional status

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Ratio? And examples?

Rankings of events or variables on scales with equal intervals and absolute zeros
Highest level of measurement
All mathematical procedures can be preformed on ratio measurements
Ex. Height, weight, pulse, bp

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Descriptive statistics?

Describe and summarize
Measures central tendency (mean, median, mode)
Measures variability (range, standard deviation)
Correlation techniques (scatter plots)

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Inferential stats?

Predict and generalize
Analyze, test hypotheses, answer research questions
Used to draw conclusions that extend beyond immediate data of the study

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Descriptive statistics: frequency distribution

Basic way to organize data

Counts the number of times each event occurs

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Measures of central tendency?

Single number describes the middle of the group

AKA summary statistics- appropriate measure depends on the level of measurement

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Mode, median, mean?

Mode= most frequent
Median=middle
Mean=average

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Modality means?

Number of modes contained in a distribution

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When all scores in a distribution are different, it is possible to

Have no mode

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Normal distribution?

Symmetric distribution

Sometimes bell shaped

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Non symmetrical distribution?

Peak of curve off center

Positive or negative skews

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Descriptive stats, measures of validity?

Spread of data 
Homogeneity?
Range
Semiquartile range 
Percentile 
Standard deviation

Inferential statistics

Allow the testing of hypotheses using data obtained from probability and nonprobability samples

Two hypotheses are tested (research/scientific and null)

Probability?

What are the chances of obtaining the same result from a study that can be carried out many times under identical conditions?
Repeated trials allows probability to test hypotheses
Sampling error
Types of errors

Type 1 error info

More serious

Can cause a type 2 error

Type 2 error

Occurs when sample is too small
May limit opportunity to measure the treatment effect (true difference between two groups)
A larger sample improves the ability to detect the treatment effect

Inferential statistics: level of significance?

Alpha level
Probability of making a type 1 error
Probability of rejecting null hypotheses
Minimum level of significance acceptable is: 0.05

Inferential statistics; statistical significance vs. clinical significance

If statistically significant, unlikely to have occurred by chance Does not necessarily imply clinical relevance

Tests of significance: nonparametric

Less powerful and flexible Used with nominal and ordinal No estimation of population parameters Distribution of data is skewed

Tests of significance: parametric

More powerful and flexible Used with interval or ratio variables Estimate of at least one population parameter Variable is normally distributed

Tests of difference

Most commonly used in experimental and quasi experimental designs t-test: statistically tests whether two groups means are different

Analysis of variance, ANOVA?

More than two groups or measurements taken more than once

Analysis of covariance (ANCOVA)

Used to measure difference among group means, but it also uses a statistical technique to equate groups under study on an important variable

Multiple analysis of variance (MANOVA)?

Used to determine the differences in group means, but it used when there is more than one dependent variable

Chi square is used when?

Used when data are at the nominal level and the researcher wants to determine whether groups are different Nonparametric

If samples are small and expected frequencies are less than 6 inches each cell what probability test is used?

Fishers exact probability

Tests of relationships do what?

Explore the association or correlation between two or more variables Usually associated with nonexperimental designs that provide level IV evidence

Pearson product moment correlation is associated with what level of measurement?

Parametric level of measurement, | Interval or ratio

Phi coefficient is used?

To express relationships when two variables being tested have only two levels Nonparametric: nominal

Point-biserial correlation is used?

To determine relationship between a nominal variable and an interval variable Nonparametric Nominal

Spearman Rho is used?

To determine degree of association between two sets of ranks as is Kendall’s tau Nonparametric Ordinal

Effect sizes? Small, medium and large?

Small: r=0.1 Medium: r=0.3 Large: r=0.5

Advanced statistics: multivariate statistics are?

Multiple regression Factor analysis Path analysis Structural equation modeling

Appraising the evidence, descriptive and inferential stats?

What descriptive statistics are reported? What level of measurement is used to measure each of the major variables? Is the sample size large enough to prevent one extreme score from affecting the summary statistics Does the hypothesis indicate that the researcher is interested in testing for differences between groups or in testing for relationships? What is the level of significance? Does the level of measurement permit the use of parametric statistics? Is the size of the sample large enough to permit the use of parametric statistic? Are the results for each of the hypothesis presented clearly and appropriately? If tables and graphs are used, do they agree with the text and extend it, or do they merely repeat it? Are the results understandable? Is a distinction made between clinical significance and statistical significance? How is it made?

Science and research.....? One studies findings are rarely sufficient to support a major practice change

Prove nothing.

Identify the level of measurement for the variable of age?

Interval

To minimize the risk of a type 2 sample error, the researcher should do what?

Increase the sample size

Which test is used to test for differences between means?

t test

Which statement regarding statistical hypothesis testing and errors is true?

Type 1 error occurs when the researcher rejects a null hypothesis that is actually true