Week Two

Question 1

Define inferences

Answer 1

Draw conclusions about parameters based on statistics

Question 2

What is sampling error

Answer 2

The difference between the population parameter and the sample statistics. Need to keep sampling error as low as possible

Question 3

How do you reduce sampling error

Answer 3

Need some random selection of participants into the sample

Randomness is crucial to probability sampling techniques

Equality of the draw; muse be equally likely to be selected

Independence of the draw: selecting one element won’t affect the sampling of any other elements

Question 4

What are the three measures of central tendency

Answer 4

Mean: arthimetic average (total of all observed values divided by the number of values)

Median: mid point value which has 50% of ranked or ordered data fall above or below

Mode: most common or frequently observed value

Question 5

What level of measurements are associated with the measures of central tendency?

Answer 5

Mean: interval or ratio

Median: ordinal

Mode: nominal or categories data

Question 6

When should you use each measure of central tendency

Answer 6

Mean: if variable is numeric and doesn’t have extreme scores

Median: if variable is numeric and has extreme scores must be at least ordinal

Mode: if variable is categorical and modal category is observed

Question 7

What is the normal curve

Answer 7

Shows the distributions of our data

The normal curve is symmetrical, no skewnesss, can be Kurtose, unimodal so only one peak

Mean, mode and medium all the same under normal curve

Bimodal: two peaks

Question 8

What is skewness

Answer 8

Concerned w the symmetry of the distribution

Skewed distribution have one side of the distribution that is different to the other

Positive skew: the tail of the graph points towards the positive end of the scale

Negative skew: the tail of the graph points toward the negative end

Question 9

What is the difference between a positive and negative skew?

Answer 9

Negative: elongated tail at the left.

Positive: enlongated tail at the right

Question 10

When is symmetry considered to be obtained with skewness

Answer 10

When the skewnesss value is -1 to 1 - aiming for zero

Question 11

What is kurtosis

Answer 11

The extent to which cases are piled up around the measure of central tendency

Question 12

What are the three difference types of kurtosis peak ness

Answer 12

Leptokurtic: values are all close to the measure of central tendency and variance and std dev smaller (lept - tall)

Platykurtic: values are spread across the distribution and variance and std dev largest (platypus - flat)

Mesokurtic: values close to normal distribution (middle- normal)