W4 Flashcards by Holly Tomlinson

CENTRAL TENDENCIES

Advantages to using the mean

Uses every value in data set

Tends to be stable in different samples

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CENTRAL TENDENCIES

Disadvantages to using the mean

Can only be used w/ interval + ratio data

Can be influenced by extreme values

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CENTRAL TENDENCIES

Advantages to using the median

Not affected by extreme values or skewed distribution

Can be used w. ordinal, interval + ratio data

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CENTRAL TENDENCIES

Disadvantages to using the median

Ignores most values in data set

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CENTRAL TENDENCIES

Advantages to using the mode

Easy to determine

Not affected by extreme values

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CENTRAL TENDENCIES

Disadvantages to using the mode

Ignores most values in data set

Can be influenced by small number of values

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SPREAD OF DATA

What comes under dispersion of data

Range

Quartiles

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SPREAD OF DATA

What comes under distance from mean value

Variance

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Disadvantage to range

Greatly affected by extreme values

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Advantage to interquartile range

Not affected by extreme values

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Disadvantahes to interquartile range

Doesn’t consider half the data set

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What 2 key concepts for inferential statistics can we derive from variance?

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What are the statistical tests that can tell us whether our data is normal enough for parametric stats

Kolmogrov-Smirnov test

Shapiro-Wilk test

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What does it mean if the p value is less than 0.05 in the Shapiro-Wilk test and the kolmogrov-smironv test

Data is NOT normally distributed

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2 tailed test

Testing for effects in both directions

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What is the sum of squared errors dependent on?

Number of values in a data set

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When looking at SPSS….

Table showing independent samples test

What are the degrees of freedom for the data set?

The df in the row stating ‘Equal variances not assumed’.

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Which measure of the spread of a data set is determined by subtracting the mean of a data set from each individual value?

Deviance

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What sample size is the Shapiro-Wilk test best for (provide a value)?

<50

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Your significance value for the Kolmogrov-Smirnov test of normality is 0.012. Does this value indicate that the distribution of your data set is normal?

if p value is less than 0.05 then test is significant so the distribution of data is probably NOT normal.

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What does the Shapiro-Wilk test assess?

Normality

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Your significance value for the Shapiro-Wilk test of normality is 0.115. Does this value indicate that the distribution of your data set is normal?

Yes

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True or False? The median is affected by skewed distributions

False

Which percentile is the lower quartile equal to?

25th

What is the term for a data set that has two numbers that occur most frequently?

Bimodal

If you calculate the average value of a data set that has been trimmed what is this called?

Trimmed mean

Your significance value for the Kolmogrov-Smirnov test of normality is 0.078. Does this value indicate that the distribution of your data set is normal?

Yes

Your output from an independent t-test reveals a p value of 0.912. Is there a significant difference between the groups?

You are conducting a paired t-test with 32 participants. What are the degrees of freedom?

You have a value for kurtosis of 1.398 and a value for standard error of kurtosis of 0.824. Does this data suggest you have a non-normal distribution?

What do we call it when two groups have the same spread of data around the mean?

Homogeneity of variance

Which type of distribution is said to have negative kurtosis?

Platykurtic

If the sample variance for your study is 524.18, what is the standard deviation?

22.89 | Square root the sample variance

Identify the lower quartile of the following data set: | 32, 26, 42, 28, 31, 41, 29, 33, 27, 37, 23

You have a value for kurtosis of 1.284 and a value for standard error of kurtosis of 0.972. Does this data suggest you have a non-normal distribution?

No (If the value for kurtosis is MORE than double the value for the SE of kurtosis you may have a non-normal distribution).

Your significance value for the Levene’stest of homogeneity of variance is 0.031. Is the assumption of homogeneity met?

No (Assumption can only be met when the homogeneity of variance is greater than 0.05).

If a data set is normally distributed what will be the value for skew or kurtosis ?

If the standard deviation for your study is 18.26 and you have 12 participants, what is the standard error?

5.27 | Divide SD by square root of sample size

You have an SPSS output that reveals a value for skewness of 0.958 and a value for standard error of skewness of 0.362. Is it possible you have a skewed distribution?

Yes | if the value for skewness is more than double the value for the SE of skewness you may have a skewed distribution

You have a value for kurtosis of 1.634 and a value for standard error of kurtosis of 0.605. Does this data suggest you have a non-normal distribution?

Yes | If the value for kurtosis is more than double the value for the SE of kurtosis you may have a non-normal distribution

Which value tells us the total dispersion of values in the data set from the mean?

Sum of squared errors

What is the easiest solution for a data set that is not normally distributed?

Collect more data

What value is calculated to counteract the effect of extreme values on the range of a data set?

Interquartile range

Your significance value for the Shapiro-Wilk test of normality is 0.026. Does this value indicate that the distribution of your data set is normal?

No As it is less than 0.05.

If the sample variance for your study is 364.22, what is the standard deviation?

19.08

You have an SPSS output that reveals a value for skewness of 0.624 and a value for standard error of skewness of 0.408. Does this data indicate a skewed distribution?

What is another term for the deviance squared?

Sum of squared errors

Which measure of central tendency is the second quartile of a data set equal to?

Median

Your significance value for the Levene’stest of homogeneity of variance is 0.091. Is the assumption of homogeneity met?

Yes

Which value is defined as the square root of a data set?

You have an SPSS output that reveals a value for skewness of 0.761 and a value for standard error of skewness of 0.523. Do you have a skewed distribution?

You are conducting a paired t-test for a study with 15 participants. The mean of the differences is 4.28 and the standard deviation is 6.36. What is the t value?

2.61

You are conducting an independent t-test. The mean for your first group is 48 and the mean for your second group is 38. SEM² for group 1 is 6.24 and the SEM² for group 2 is 5.46. What is the t value?

2.92

What test is used to examine the homogeneity of variance?

Levene’stest

Equation to calculate t value from independent samples t test