EBDM Lecture 9: Statistical Analysis I

What is the most simple method of charting data?

Data in Table

Which method of charting data categorizes the values by the digits?

Stem-and-Lead Plot

On a frequency distribution table, what is relative frequency?

Percentage of data that falls into the value

On a frequency distribution table, what is cumulative frequency?

Sum of above relative frequencies

Which method of charting data shows a visual representation of the count?

Bar Chart

What are the four basic types of measurements?

1. Categorization

2. Rank Ordering

3. Interval Ordering

4. Numerical Scoring

What is the measurement scale of categorization?

Nominal

What is the measurement scale of rank ordering?

Ordinal

What is the measurement scale of interval ordering?

Interval

What is the measurement scale of numerical scoring?

Ratio

What is the most simple measurement scale?

Nominal

What are numbers in nominal measurement only used as?

Labels to represent the category

Is the order of categories in nominal measurements meaningful?

No

Is the numerical order meaningful in ordinal measurements?

Yes

Is there implied size for each category in ordinal measurements?

No

Is there a true zero value in ordinal measurements?

No

What do numbers act as in ordinal measurements?

Labels

Is the numerical order meaningful in interval measurements?

Yes

Is there implied size for each category in interval measurements?

Yes

Is there a true zero value in interval measurements?

No

Are statistical manipulations allowed with interval measurements?

Yes, but limited

Are interval measurements common or rare?

Rare

Is the numerical order meaningful in ratio measurements?

Yes

Is there implied size for each category in ratio measurements?

Yes

Is there a true zero value in ratio measurements?

Yes

Are statistical manipulations allowed with ratio measurements?

Yes

If a variable has only two categories, what scale must it be on?

Nominal

What are variables with two categories called?

Dichotomous

What are nominal and ordinal variables described as?

Categorical (Discrete)

What are interval and ratio variables described as?

Continuous

What is the most frequently occurring value in a group of observations?

Mode

Which measurement scales is mode appropriate for?

All four

What is the value that is in the middle of a group of observations (50th Percentile)?

Median

Which measurement scales is median appropriate for?

Ordinal

How can you calculate the median?

Order the values and choose the middle number (average of two middle numbers if odd)

What is the average of the observations?

Mean

Which measurement scales is mean appropriate for?

Ratio

How can you calculate the mean?

Add all values and divide by number of values

What are the main measures of dispersion?

1. Range

2. Standard Deviation

3. Standard Error

What is the difference between the highest and lowest observations?

Range

Which measurement scales is range appropriate for?

1. Ordinal

2. Interval

3. Ratio

What represents the average, absolute distance of each individual observation from the mean?

Standard Deviation

Do bigger standard deviations indicate greater or less variability?

Greater

Which measurement scales is standard deviation appropriate for?

Ratio

What is the difference between standard error and standard deviation?

Standard error is inferred back to the larger population

Which measurement scales is standard error appropriate for?

Ratio

What are the two types of hypotheses?

1. Null

2. Alternative

What are null hypotheses used to describe?

No relationship between the variables of interest

What does a non-directional alternative hypothesis show?

Any possible relationship

What does a unidirectional alternative hypothesis show?

One specific relationship

If the null hypothesis is rejected, what is the strength of the relationship?

Statistical significant

What does chance of misrepresentation result from in research?

Process of selecting a study sample

What represents the probability of obtaining the observed result by chance?

p-value

If the p-value is small, how likely is it that the result is due to chance?

Less likely

What is the greatest p-value that still shows that the data is significant?

0.05 (5%)

If the relationship between the exposure and outcome is statistically significant, then what is the relationship?

1. Exposure groups have different outcomes

2. Exposure and outcome are correlated

Is exposure categorical or continuous?

Categorical

Is outcome categorical or continuous?

Can be either

What is the statistical test used to assess whether there are group differences for categorical outcome variables?

Chi-square Test

What kind of data table do Chi-square Tests rely on?

Row x column

What do Chi-square Tests calculate?

Variance between observed and expected values

What is the statistical test used to assess whether the means of 2 independent groups are statistically different from each other?

Independent t-test

What is the statistical test used to assess whether the means of 3+ independent groups are statistically different from each other?

ANOVA

Are t-tests and ANOVA used for categorical or continuous variables?

Continuous

What does the F-test statistic measure?

Difference in the means across the groups

Can the F-test tell us which groups are different?

No

If doing a Chi-square test on a group of 2 for a categorical variable, is post-hoc testing necessary?

No

If doing a Chi-square test on a group of 3+ for a categorical variable, is post-hoc testing necessary?

Yes

If doing a t-test for a continuous variable, is post-hoc testing necessary?

No

If doing ANOVA for a continuous variable, is post-hoc testing necessary?

Yes