Flashcards in 767 Midterm Notes (Imported) Deck (294)

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239

## What is the effect of increasing sample size on variance?

### Decrease in variance as you come closer and closer to the "true" value in the population

240

## What are the characteristics of the normal curve?

### 1. Unimodality 2. Symmetry 3. Mathematical properties

241

## What are properties of Z scores?

### Standard scores with SD of 1, mean of 0, and range from -3 to 3.

242

## What percentage of scores fall within +/- 1 SD of the mean in a normal distribution?

### ~68%

243

## What percentage of scores fall within +/- 2 SDs of the mean in a normal distribution?

### ~96%

244

## What percentage of scores fall within +/- 3 SDs of the mean in a normal distribution?

### ~99%

245

## How does one use the Normal Probability Curve of frequency data to interpret data?

### Specify the probability that chance events will occur (e.g., - Chance of something occurring outside of range of Z2 is 4%, outside of Z3 is 1%.)

246

## How does one calculate the Standard Error of Means?

### SD (population SD approximated by sample SD) divided by the square root of cases in the sample

247

## What is the standard error of the mean?

### a standard deviation of an infinite number of means, only chance error makes them fluctuate

248

## What does it mean for a model to be linear?

### No terms have powers greater than 1.

249

## What is the theoretical rationale of the t-ratio approach?

### When we compare two means we want to ask do the means differ significantly? Or is the difference within the bounds of chance? (e.g., Does A differ from B beyond the difference expected by chance?)

250

## What is the theoretical rationale of the Analysis of Variance Approach?

###
- A difference of two or more groups can be tested for significance.

- This method uses variance entirely and pits two variance against one another.

- One variance (independent, or experimental variable) pitted against a variance due to error or randomness

- Compare the “between group variance” with the “within group variance”

251

## What is within group variance?

### variance of the means of the groups

252

## What is standard variance of the mean?

### standard error of the mean squared

253

## What is the F-Ratio?

###
1. Between Group Variance / Within Group Variance

2. - Your results are compared to F table. If higher than said number on the table, then results are significantly significant

254

## How do F and T relate to one another?

###
- F= t^2

- t= (square root of) F

255

## When does one use an F test over a t test?

### - When comparing more than two groups F is used (t for two groups only).

256

## What is the effect on mean of adding a constant to all variable scores?

### Increases mean

257

## What is the effect on variance of adding a constant to all variable scores?

### No effect on variance

258

## What is the effect on between-group variance of adding a constant to all variable scores?

### Changes between group variance

259

## What is the effect on within-group variance of adding a constant to all variable scores?

### Does not affect within group variance

260

## What is the relevance to the F test of not having independence of between group and within group variance?

### F-test assumptions are violated

261

## In Calculating of One Way Analysis of Variance, SSt = (equation)

### SSb + SSW

262

## In Calculating of One Way Analysis of Variance, SSt is (words)?

### Sums of Squares Total

263

## In Calculating of One Way Analysis of Variance, - SSb

### Between Sums of Squares

264

## In Calculating of One Way Analysis of Variance, - SSw

### Within Sums of Squares

265

## What does significance of T or F tests tell us?

### That it is likely that an effect exists (is unlikely to be due to error)

266

## What does significance of T or F tests not tell us?

### Significance does not tell us magnitude of the effect/relation

267

## What is factorial analysis of variance?

### two or more independent variables vary independently or interact with each other to produce variation in a dependent variable

268