Midterm #1 Flashcards by Ailsa McLellan

What is this an example of?

Where did you go to high school?
A. Victoria Region (1)
B. Vancouver Island, outside of Victoria (2)
C. Vancouver lower mainland (3)
D. B.C. but outside of Vancouver Island and lower
mainland (4)
E. All other places (5)

Categorical data

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Which of the following is an example of
categorical data?
A. Height measured in feet
B. Daily rainfall in mm
C. Hair colour
D. Typing speed in wpm
E. Weight measured in pounds

C. Hair Colour

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What type of data measures frequency/count data?

Categorical

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A score on a personality test or time it takes to run a

km represents what type of data?

Measurement data

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When values can only take on certain values.
No possible value between units in a scale.
Eg. You can’t have 2.4 kids.

Discrete variables

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Variables that can be any value within a range of numbers.

Continuous variable

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The variable that is the predictor – feature of the study used to predict or explain the behaviour.
The researcher controls what the participant is exposed to.

Independent variable

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Some participants get malibu in their punch others do not. Researchers want to find out the behavioural effects of the malibu. What is the malibu in the study?

Independent variable

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Which variable: The characteristic the researcher is accounting for or predicting
• Behavioural 
• Attitudinal -feelings
• Cognitive
• Physiological

Dependant variable

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Can blueberries slow down aging? A study indicates that antioxidants found in blueberries may slow down the process of aging. In this study, 19-month-old rats
(equivalent to 60-year-old humans) were fed either their standard diet or a diet supplemented by either
blueberry, strawberry, or spinach powder. After 8 weeks, the rats were given memory and motor skills tests. Although all supplemented rats showed improvements, those supplemented with blueberry powder showed the most notable improvement.

What is the IV? Is it manipulated or measured?

diet

manipulated

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Can blueberries slow down aging? A study indicates that antioxidants found in blueberries may slow down the process of aging. In this study, 19-month-old rats
(equivalent to 60-year-old humans) were fed either their
standard diet or a diet supplemented by either
blueberry, strawberry, or spinach powder. After 8 weeks, the rats were given memory and motor skills tests. Although all supplemented rats showed improvements, those supplemented with blueberry powder showed the most notable improvement.

What is the DV?

memory and motor skills

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A technique for making sure that every individual in a population has an equal chance of being in your sample.

Random sampling

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Give an example of why measurement scale is important

5 and #8 is very different on a jersey than in terms of placement

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What type of scale measures categories of things? Eg. favourite colour

Nominal

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What is important about setting up the choices for a nominal scale?

Categories are equivalent and discriminable: one is
not better than or higher than the other(s) and can
be distinguished from each other. Do not place choices in a ranking order.

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What type of scale measures “more of”?

Ordinal

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Bronze, Silver, Gold. What is this an example of?

Ordinal

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Very dissatisfied, somewhat, neither, somewhat, very.

What is this an example of?

Ordinal ordering. Does not specify HOW MUCH. We know more of, but not the exact units/if they are equal.

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Scale that measures “how much more of” or “how many units more?”

Interval scale

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What is a key distinguishing feature of interval scales?

Numerical scale where intervals have the same
interpretation throughout (eg 20C, 40C dif=20C//80C, 100C dif=20)
BUT cannot speak truthfully about ratios, does not have a true zero. (eg: C to Far does not have an equal ratio difference)

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Scale that is an interval scale but has an absolute 0, a true absence of the quantity being measured, a true zero point.

Ratio scale

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Is money an example of nominal, ordinal, ratio of interval?

Ratio. True zero point: $0 = no money, If you have $50, you have twice as much money as someone who has $25.

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What is this an example of:
What kind of phone do you have?
a) Android
b) Blackberry
c) iphone
d) Non-”smart” phone
e) No phone

Nominal

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Memory experiment: Number of items correctly
recalled
What type of scale is this?

Ratio
Someone who recalled 6 items recalled twice as
many items as someone who recalled only 3 items.
Someone can get 0 items correct and it means that
they have an absence of (no items) recalled.

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How do you set up a frequency graph?

level, f, cum f, rel f, cum rel f. 3 2 1

How do you determine the relative frequency? (rel f)

rel f= f/N | N=total

If the relative frequency is 0.205 what does this mean?

20.5% of whatever

How do toy determine cumulative frequency (cum f)

Frequency of scores at or below a particular score.

How do you determine the cumulative relative frequency?

cum f/N | Answer should be 3 decimal places!!

When do you use bar graphs? What kinds of scales?

Used when IV is nominal or ordinal.

What is visually different between a bar graph and a histogram?

The bars touch in histograms.

When do you use histograms?

Used when IV is interval or ordinal

When is using a line graph/frequency polygon useful?

Good for understanding the shape of distributions, useful for comparing distributions.

When do you use a line graph?

When the IV is interval or ratio.

If you want compare what method of transportation PSYC 300A students use to get to school (bus, bike, car etc.) What type of graphic display would you use?

Bar graph

Which axis presents the DV vs IV?

``` DV= y-axis IV= x-axis ```

When making a grouped interval table what are the 3 requirements for the intervals?

1. Equal in width 2. First value of every interval is a multiple of the interval width (width=10, 1st value of every interval needs to be divisible by 10) 3. Lowest interval includes the lowest datum value

What is the real limit of the interval 70-79?

69.5-79.5

When making a grouped interval in a histogram what do you mark on the x-axis?

Mark the midpoint of the interval.

What is the modality?

The number of meaningful peaks in a frequency distribution of the data.

What does a unimodal, bomidal and non modal graph look like?

Unimodal= one apparent peak Bimodal=two apparent peaks Non-modal=no peaks

What does a positive skewed graph look like?

Frequent scores are clustered at the lower end and the tail points towards the higher or more positive scores

What is kurtosis?

Degree to which data values are distributed in the tails of the distribution.

A graph with a flattened middle and high, short tails. Big space between axis and curve.

Platykurtic.

A graph with a tall, narrow, high peaked-middle. Low, long, skinny tails; little space between axis and curve.

Leptokurtic.

The most commonly occurring score. (greatest frequency) that corresponds to the highest point of a distribution.

The mode.

What type of scale is the mode best for?

Nominal

Can you only have only one mode?

LOL NOOO. If there are 2 nonadjacent scores with equal-ish frequency, we can say the distribution is bimodal and report both scores.

Is the mode affected by the presence of extreme scores?

No!

What does the mode represent?

The largest number of people having the same score.

What is the main disadvantage of the mode?

It may not reflect many other aspects of the distribution. You can change some scores in a distribution without affecting the mode. --But affects other measures like the mean.

Which of the following statements about the mode is FALSE? a) It must be an actual score that occurred in the data set. b) It can consist of more than one number. c) It can be calculated algebraically.

C) It can be calculated algebraically

The middle score in an ordered set or data

Median

How do you determine the median? (formula)

Mdn= (N+1)/2

What type of data scales can you use the median? Which one is it best for?

Can be used on data from ordinal, interval and ratio scales. Best for ranked data (ordinal scale). Also used when interval and ratio data are very skewed.

How is the median affected by extreme scores?

Not affected!

How do you calculate the mean?

value for the arithmetic average mean= sum of all x/N sum of all values divided by total number of scores

What type of data scales do you use the mean?

Used for interval or ratio data.

How is the mean affected when data are strongly skewed?

It is unreliable/biased.

Which of the 3 measures of central tendency can be measured with algebra?

The mean.

What is different about the mean's value in comparison to the mode and median?

It doesn't not necessarily reflect any actual value in the dataset.

Variable: Number of chocolate chips in cookies. What | scale of measurement is this?

Ratio

A measure of variability calculated by subtracting | the lowest score from the highest score

Range

What type of measurement scales can you use range for?

Ordinal, interval, ratio scales

What are the 2 disadvantages of Range?

Derived from only 2 values- often the least frequent values | -unreliable: sensitive to extreme values

What is the interquartile range?

The range of the middle 50% of the observations | -reflects values between the 20 and 75th percentile portion of the distribution of data in relationship to the median

What type of measurement scales can be used for interquartile range?

Can be used for ordinal, interval and ratio.

What’s the advantage of using the interquartile range compared to the range? A. Can be used with ordinal, interval and ratio scales B. It is less susceptible to outliers because you don’t take into account extreme values C. Uses the full range of the data D. Based on 2 values

B) It is less susceptible to outliers because you don't take into account extreme values

How do you determine the median absolute deviation?

1. Find the median for a set of data 2. Take absolute deviation of ea. value 3. order high to low 4. Take median of the ordered deviation value

Is Standard deviation or the median absolute deviation more sensitive to extreme scores or skews?

SD is more sensitive

What are the 2 disadvantages of the median absolute deviation?

1. provides a limited description of variability | 2. Not useful in advanced statistical procedures

Find the median absolute deviation for this set of data: | 7, 8, 10, 10, 12

Answer= two

What does average deviation determine?

How much each score deviates from the mean | [E(X-mean)]/N

∑ (X − Mean)^2= SS | What does this determine?

A minimum

What happens if you use the mode or median instead of the mode when determining variance?

Neither would produce a smaller value than deviation from the mean.

What is the definition of variance?

The average of the squared deviation scores.

When would you divide Variance by N-1 rather than N?

You use the N-1 approach when you have scores from a particular group of people and you want to estimate what the variance would be for the larger group of people whom these individuals represent (inferential statistics)

How are standard deviation and variance related?

Standard deviation is the square root of variance so it can return to the original units of the measure

What is the most reliable measure of variability?

Standard Deviation

Is the standard deviation sensitive to extreme scores or outliers?

YES

What should you use if distribution of scores is severely skewed how should you describe the data?

Use the median and the median absolute deviation

A researcher is interested in the variability of hyperactivity in children. On a test with 15 possible points, the children’s scores were: 6, 8, 4, 10, 2. Find the standard deviation

M=6 SS=40 SD^2=8 SD=2.83

Absolute measure of how many physical units values deviate from the median

Median Absolute Deviation (MAD)

How much each score deviates from the mean

Average Deviation

The average of the squared deviations from the mean.

Variance (SD^2)

The typical amount that each score varies (deviates) from the mean.

Standard deviation

The range of the middle 50% of the observations.

Interquartile range

``` What measure of spread (variability) is best on data that is normally distributed? A. Range B. Interquartile range C. MAD (Median Absolute Deviation) D. SD2 (variance) E. SD (standard deviation) ```

Standard deviation (SD)

``` What measure of spread (variability) is best on data that severely skewed? A. Range B. Interquartile range C. MAD (Median Absolute Deviation) D. SD2 (variance) E. SD (standard deviation) ```

MAD Median Absolute Deviation

What are the values in a normal distribution for skew statistic values?

Between 0 and |0.5|

How do you describe the data with a normal skew distribution?

Use Mean and SD

What are the values for a mild to moderate skew distribution?

Between |1.0| and |0.5|

How do you describe the data with a mild to moderate skew?

Use Mean and SD

What are the values for a moderate to strong skew distribution?

Greater than |1.0|-|2.0|

How do you describe the data with a moderate to strong skew?

Use Mean and SD if closer to 1 (<1.5) than 2

What are the values for a severe skew description?

Greater than |2.0|

How do yo describe the data with a severe skew?

Use Median and MAD

How do we know whether a distribution is severely or mod or mildly skewed?

You look at the sign and value | Value gives the degree of skew, sign gives direction

With these values, determine the direction of skew and the skew description as well as how you would describe the data. Mean = 2.00, Median = 6, SD=6.55

``` [3(2-6)]/6.55 =-1.83 Neg value=negative skew Value= |-1.83|>|1.0| This means a moderate to strong skew in the distribution and we should use the median and MAD to describe the data. ```

Many individuals, after the loss of a job, receive unemployment compensation until they are re-employed. Consider the distribution of time to re-employment as obtained in an employment survey. One broadcast said that the average time until re-employment was 4.5 weeks. Another one reported that the average was 9.9 weeks. One of your colleagues wanted a better understanding of the situation and learned (through a Google search) that one report was referring to the mean and the other to the median and that the data is positively skewed. Knowing that you are a statistically-savvy person, your colleague asked you which is most likely the mean and which is the median? A. 4.5 is the mean and 9.9 is the median. B. 4.5 is the median and 9.9 is the mean. C. Neither (A) nor (B) is possible. D. I am not a statistically-savvy person, so how should I know?

B. 4.5 is the median and 9.9 is the mean

You have a dataset with the following values: 20,32,18,43, and 27, Which value would produce a minimum (the smallest possible value), in the following equation for squared deviations: ∑(X − __)^2 A. 27 B. 28 C. 30 D. 32

28 | b/c mean as a balance point- this value will be less than any other SS around the distribution

What 4 things go into a written report of descriptive measures? (measures of central tendency and variability)

Describe the number of participants (and type of participant) • Describe the scale (including a description of the end points and interpretation) • Describe the mean, median, and mode, where appropriate • Describe the standard deviation, skew, and median absolute deviation (where appropriate)

Midterm #1 Flashcards

(102 cards)