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Which one to use

January 16, 2013 11:00 pm / Leave a comment

binomial: where there is just a few catagories. and there is a reference value.

one sample t test measure one value against another.

dont use the work majority unless value = more then 50%

One sample T test and Binomial

January 15, 2013 6:13 am / Leave a comment

Binomial Test Options (One-Sample Nonparametric Tests)

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The binomial test is intended for flag fields (categorical fields with only two categories), but is applied to all fields by using rules for defining “success”.

What it does: The One-Sample T Test compares the mean score of a sample to a known value. Usually, the known value is a population mean. ∞

Binomial or T Test

January 15, 2013 6:06 am / Leave a comment

To select the right test, ask yourself two questions: What kind of data have you collected? What is your goal? Then refer to Table 37.1.

	Type of Data
Goal	Measurement (from Gaussian Population)	Rank, Score, or Measurement (from Non- Gaussian Population)	Binomial (Two Possible Outcomes)	Survival Time
Describe one group	Mean, SD	Median, interquartile range	Proportion	Kaplan Meier survival curve
Compare one group to a hypothetical value	One-sample ttest	Wilcoxon test	Chi-square or Binomial test **
Compare two unpaired groups	Unpaired t test	Mann-Whitney test	Fisher’s test (chi-square for large samples)	Log-rank test or Mantel-Haenszel*
Compare two paired groups	Paired t test	Wilcoxon test	McNemar’s test	Conditional proportional hazards regression*
Compare three or more unmatched groups	One-way ANOVA	Kruskal-Wallis test	Chi-square test	Cox proportional hazard regression**
Compare three or more matched groups	Repeated-measures ANOVA	Friedman test	Cochrane Q**	Conditional proportional hazards regression**
Quantify association between two variables	Pearson correlation	Spearman correlation	Contingency coefficients**
Predict value from another measured variable	Simple linear regression or Nonlinear regression	Nonparametric regression**	Simple logistic regression*	Cox proportional hazard regression*
Predict value from several measured or binomial variables	Multiple linear regression* or Multiple nonlinear regression**		Multiple logistic regression*	Cox proportional hazard regression*

Z Score

January 15, 2013 4:26 am / Leave a comment

How many standard deviations from the mean translates to what is the z score…

longhand version.

score / SD =

mean / SD =

Mean – Score = z score

score – mean =

answer / SD = Z score

It is also possible to calculate how many standard deviations 1.85 is from the mean

How far is 1.85 from the mean?

It is 1.85 – 1.4 = 0.45m from the mean

How many standard deviations is that? The standard deviation is 0.15m, so:

0.45m / 0.15m = 3 standard deviations

this is called standadising

Z-Scores

To obtain Z-scores, go to the Analyze menu, choose Descriptive Statistics, then Descriptives. Move the variable(s) for which you would like to create Z-scores into the Variables box. In the example below, we used the variable called “rosen.” Before you click OK, be sure that the box marked “Save Standardized Values as Variables” is checked.