1. Which is the average score in a skewed distribution:

• correlation
• median
• mean
• mode

2. The median is a measure of:

• central tendency
• stratification
• dispersion
• skew

3. Which statistic should you calculate to test for commonality:

• correlation
• regression
• ANOVA
• t-test

4. What do you do if the calculated value is close to but not quite at the critical value:

• partition the null
• stratify the null
• accept the null
• reject the null

5. A distribution with the mode higher than the mean is:

• negatively skewed
• positively skewed
• bimodal
• normal

6. Given the following information:

•  SSx = 44.7
• stdevY = 3
• r = .4
• t= 2.73

Calculate the coefficient of nondetermination:

7. Given the following information, calculate F:

                       SS          df         ms
Between       120           2
Within            24         12
Total             144.        14

F =

8. Intelligence tests primarily use what level of measurement:

• nominal
• ordinal
• interval
• ratio

9. A standard deviation is the:

• square root of variance
• sum of squared-Xs
• percentage of variance understood
• tangent of slope

10. The 95th percentile corresponds which z score:

• – 1.5
• – 1.0
• + 1.64
• + 1.96

 

Answers after this graphic!

 

Answers

1. Which is the average score in a skewed distribution:

• correlation
• median
• mean
• mode

2. The median is a measure of:

• central tendency
• stratification
• dispersion
• skew

3. Which statistic should you calculate to test for commonality:

• correlation
• regression
• ANOVA
• t-test

4. What do you do if the calculated value is close to but not quite at the critical value:

• partition the null
• stratify the null
• accept the null
• reject the null

5. A distribution with the mode higher than the mean is:

• negatively skewed
• positively skewed
• bimodal
• normal

6. Given the following information:

•  SSx = 44.7
• stdevY = 3
• r = .4
• t= 2.73

Calculate the coefficient of nondetermination: 1-rSquared = .84

17. Given the following information, calculate F:

                       SS          df         ms
Between       120          2.         60
Within            24         12           2
Total             144.        14

F = 30

8. Intelligence tests primarily use what level of measurement:

• nominal
• ordinal
• interval
• ratio

9. A standard deviation is the:

• square root of variance
• sum of squared-Xs
• percentage of variance understood
• tangent of slope

10. The 95th percentile corresponds which z score:

• – 1.5
• – 1.0
• + 1.64
• + 1.96

 

 

 

Photo by AbsolutVision on Unsplash

Degrees of freedom

SSregression = SStotal * rsquared

SSerror = SStotal * (1- rsquared)

SStotal = SSy

df(regression) = k – 1

df(error) = N – k

df(total) = N-1

F = mean squares regression divided by means squares error

 

Formula for Central Tendency

MEAN.

You probably already know this formula. A mean is the average of scores. We like to use it becuase we don’t have to arrange the scores in any particular order before calculating it. We just add up all the numbers and divide by the number of scores. In statistical vocab we “sum” the numbers and divided the sum by N (the number of scores).

∑X/N

MEDIAN

A median requires that we put the numbers in order (from high to low, or low to high). The median is the score in the middle (if there are an odd number of scores) or the average of the two middle-most scores (if there are an even number of scores). That too much work, so we prefer the mean.

There is no easy formula for median.

MODE

The mode is the most popular score (most common). If you plot a distribution, the mode will be the highest spot on the distribution. It will be the top of the mountain. If your mountain has more than one peak, the distribution will be bimodal (2 high spots) or multimodal (several high spots).

There is no easy formula for mode.